Harry is called out to a death at a racecourse. A jockey was killed when his horse pulled up and fell, crushing him to death.

The police and Harry find that a group of doctors are in a syndicate that owns race horses. One is a kidney Specialist and another is a Plastic Surgeon with a gambling problem. A young woman is going to pay for a kidney transplant privately as the National Health Service wait list is long. She and her husband wish to have a baby after that. There is a helicopter accident and it all becomes a complicated story to figure out for the team of Pathologists who have a temporary visitor called Nicki who is borrowing the lab to obtain a narrative about an Iron Age family whose bones she has to examine.

The team investigates the derailment of a train caused by someone leaving Maj. Mark Wiltshire's Land Rover on the tracks. The army is suspected but Wiltshire was in the officers mess at the time. The team have yet to identify the 21st victim, or determine if that person was on the train or in the car. Working with a survivor's group, they try to re-create where everyone was seated just prior to the crash occurring. When one of the survivors commits suicide, the crash claims its 22nd victim.

The investigation continues and one of the survivors remembers a vital piece of information. It becomes evident that the identification of body 21 may also lead to the cause of the crash. In the end, the solution rests on discovering a an unknown romantic affair and marital betrayal.

The team is shocked when Leo Dalton's wife and daughter are killed when a fancy sports car careens out of control and smashes into a café. The police are puzzled by the cause of the crash but believe the driver may have been involved in a identity theft ring when they find several several passports and ID cards in the vehicle. Meanwhile, Nikki must perform urgent autopsies on two bodies found floating in the river. When she finds fingerprint evidence linking one of the bodies to the car accident, it becomes apparent that the two cases are linked and the police may have been less than forthcoming about their investigation.

Unsatisfied with the progress of the case, Leo Dalton takes matters into his own hands trying to get in contact with an identity theft ring. The information he gathers assists the police and they work together. The death of one of the gang members, and a vital clue, lead police to identify the their leader, but in the end, the solution brings little solace to Leo.

The team is called to a drive-by shooting outside a London nightclub. They arrive to a scene of carnage with several people dead, or dying.

With the murder of the club manager, the pathologists also determine that the club owner shot his own girlfriend, likely by accident. They also identify an unlikely suspect in the shooting of the club manager. Harry and Nikki confront Leo over his abusive and unprofessional behavior.

Harry investigates the death of a woman who drowned in a backyard pool. She was apparently struck on the side of the head and her husband claims that her expensive necklace is missing. Leo and Nikki investigate the death of Lucie Philips, a kidnap victim who was taken a week previously. The girl's father tried to pay the ransom but the money was never collected leading the police to believe that the kidnappers may have had other motives. They also investigate the murder of a pizza deliveryman that has similarities with the Philips crime scene. A third murder leads the police to suspect that they may be seeing the work of a serial killer. Nikki's grandmother dies bringing her into contact with her estranged father.

Leo and Nikki find yet another victim who was apparently bound and buried alive. However, they continue to have difficulty finding a common link among all of the victims. The investigation focuses on the editor of a philosophical journal who had an intellectual disagreement with one of the victims but the case is more complex than first imagined. Harry discovers that his drowning victim was pregnant which may have indirectly contributed to her death. Nikki's father is released from prison and promptly disappears.

The team investigates two deaths, the first a suicide where someone jumped to their death and the second where a paranoid schizophrenic dressed as a vicar goes on a rampage stabbing innocent bystanders. Their suspicions are aroused when they learn that both men were receiving treatment at the same clinic, January House. Leo assists the police in their investigation of a building society employee who is forcibly taken from his house and subsequently found dead in his own car. Harry is asked to perform an autopsy and provide a second opinion in the death of a young woman. The death was ruled a suicide, but the mother refuses to accept the verdict.

The Director of January House tries to take his own life on the clinic grounds and the pathologists suspect they may have a case of adulterated prescription medication. Harry's repeat autopsy reveals that the young woman was also under medicated, but she had no contact with the clinic. The police suspect the wife in the case of the building society employee and Leo sets out to disprove her time line.

When a boat carrying illegal passengers is found crashed in the Thames, the team investigate.

The team follows the trail of the people traffickers, and has to find any remaining survivors before a highly contagious disease breaks.

Harry investigates a case of hit and run where the victim was a 16 year old boy from the nearby housing estate. Working with Sgt. Susan Fenn, they attempt learn if this was an accident or intentional. Harry takes quite a liking to Susan and is shocked by a sudden turn of event. Leo examines a death resulting from a house fire where the lady of the house died. He is puzzled at why she was unable to leave and the police immediately suspect the husband, who was in a nearby park with the children, of murder. Nikki looks into the case of a young woman who collapses at her hen night. She had recently had minor surgery and was taking pain killers, but there is surprising information to be found about her background.

The pathologists busy week continues with a variety of cases. Nikki examines a death in a telemarketing office. Several workers were vying for promotion and the police suspect foul play. Harry deals with the case of a professional footballer who committed suicide. He realizes there is a link to another case he is working on. Leo deals with the case of a drunk who died on a bus. There is little information about the man and the case becomes more of a puzzle when the autopsy reveals that he wasn't drunk at all.

Harry is shocked when his former university girlfriend, Penny Harris, is brought in dead. She drove her car into a tree and the police initially suspect suicide but the autopsy reveals that the medication in her system was ground rather than in pill form, so they conclude she was likely murdered. Her husband tells the police that he thought his wife was having an affair and her parents react strangely to the news. Leo assists the police in the death of Jimmy Triangle, a conceptual artist whose latest work dealt with the death of conceptual art - and includes his own body, as he is shot through the head. The question is whether the shot was self-inflicted or not.

Nikki and Harry continue to investigate the death of Penny Harris. Harry is shocked to learn that she had apparently at some point in her life had a child but her husband denies any knowledge of such. Another death in the Harris family allows them to narrow the suspects and identify the killer. Leo continues to look for clues and the police think they have solved the case through fingerprint evidence, but Leo is able to prove that the suspect has been framed. The victims penchant for videotaping his activities provides a vital clue.

Alison Garland is a 14 year old schoolgirl found dead on the school grounds just after lunch. She appears to have slit her wrists and committed suicide, but there is also evidence that she had sexual relations just earlier that day. As Leo Dalton looks into the case he learns that Alison was also a school bully and was a very unhappy young woman. Harry assists the police in the stabbing death of a car dealer. The evidence suggests that he was stabbed in his garage and his body then dumped. The case takes a radical twist when they find that the knife found by Alison's body was also used to kill the car dealer. Nikki assists the police in the death of an elderly woman who appears to have been maltreated.

A third murder is discovered on school grounds and Leo realises the killings are connected to a sinister teenage pact. Meanwhile, Nikki proves her elderly victim died of hypothermia - but there is still a guilty party to be caught.

Harry and Nikki deal with the case of a young woman who is found dead in an animal shelter. Her dead body has obviously been posed and the autopsy reveals she may have been tortured before death. Information from police intelligence suggests that they may be dealing with a group of radical animal rights activists. It all becomes quite personal for Harry when Nikki is taken prisoner. It's also a difficult time for Leo who has been asked to appear before a medical council hearing and testify on the propriety of a close friend's medical research. Harry has been offered a prestigious chair at an American university, but has had difficulty discussing the issue with his colleagues, especially Nikki.

Harry and the police desperately search for Nikki as they continue to find more bodies. The animal rights activists' target is a well known pharmaceutical firm that is undertaking research on behalf of the government. Leo finally decides on a course of action in testifying at the medical council hearing.

The pathologists investigate when a military helicopter crashes into a refugee detention center. Harry and Nikki actually witnessed the crash and were first on the scene but the case is complex since the center was Ministry of Defense property leased to the Home Office. The team is shocked at the conditions they find in the center and Harry, who has a close friend in the RAF, is shaken when a government Minister attributes the accident to pilot error.

Harry is convinced that the RAF is trying to cover up the real reasons for the crash. This is re-enforced when the dead pilot's father tells him that no one liked or trusted the particular type of helicopter that crashed. When given a chance to perform the post-mortem on the pilot, they find a possible physical cause however. In examining one of the dead refugees, Nikki concludes that he had undergone plastic surgery. She attempts a facial reconstruction to see if they can identify him.

Leo Dalton investigates the death of a young boy whose body is found in the river. He was badly abused and his hands and feet were severed. The child is found to have been HIV positive and the pathologists determine that he may have been the victim of a ritual killing., perhaps as part of an exorcism that went too far. When the skeletal remains of another child are found, Leo believes the police have focused their investigation on the wrong man. Nikki Alexander investigates the apparent suicide of Father Anthony Reid who appears to have jumped from his apartment window on the grounds of a well-known Catholic school. He had colon cancer but those who knew him question that he would take his own life. Harry Cunningham looks into the case of Austin Chambers who is found floating in his swimming pool with an obvious ligature mark on his throat.

When a second person, Vincent Fricks, is found dead with ligature marks around his neck, Nikki and Harry not only find a connection between the two dead men but also with the school where Father Reid committed suicide. They also find another common link between the three. Leo Dalton continues his investigation into a local church that combines Christian with African beliefs and customs. He manages to find physical evidence linking one of the dead boys to the church.

Harry Cunningham investigates when a car accident reveals two bodies inside one coffin. The coffin contained the body of 80-year-old Ethel Mortimer, who was supposed to be there and also that of James Featherton, a high tech sales rep who also had a heavy cocaine habit. Leo Dalton and Nikki Alexander have to deal with the death of a young child who died post-operatively. The pediatric surgeon in the case, Alice Huston, is well known in her field but may be prone to undertaking aggressive surgeries. The pathologists find a connection between the two cases when Featherton's girlfriend is found to be a nurse on Huston's surgical team.

With Claire Kowalski missing and Nikki Alexander unconscious from a blow to the head, Harry and Leo investigate exactly what is going on at the hospital. Harry discovers that a member of Huston's surgical team is not who they claim to be and has actually stolen the identity of someone who died six years before. Blackmail is at the center of it all and it turns out Alice Huston is hiding a secret. However, the killer is identified only by looking to old friendships and the calling in of an old debt.

Nikki Alexander finds herself working on a case from her past. Four years previously, she had been instrumental in getting 17 year-old Anna Holland acquitted of a murder charge. She had been accused of egging on her boyfriend in the murder of a young mother they chose randomly. Now, while under police protection, her body has been found in a burnt car. The autopsy reveals that she had been stabbed but had died from carbon monoxide poisoning and so was burnt alive. Nikki also receives a surprise visit from her estranged father who wants her to perform a second autopsy on a friend who recently died.

Nikki Alexander begins to have serious doubts about her conclusions four years previously when her testimony helped acquit 17-year-old Anna Holland of murder. Anna's mother had withheld information from the police and as Nikki reconstructs the scene of the crime, she realizes that the blood spatter evidence no longer holds up. The police focus on the dead woman's husband but the pathologists find that a series of unsolved murders may have a bearing on the case. Nikki is also annoyed with her father, who has conned Harry Cunningham into completing a second autopsy on his late wife.

Harry Cunningham is asked to review a case in a insurance dispute. The insurance company is refusing to pay out on an policy when the autopsy results show that the woman was intoxicated and likely was responsible for the fall that killed her. Her family insists that that is impossible as she was an abstainer. Nikki Alexander investigates when human remains are found buried in an field. The locals believe the body to be that of Clara Young, who had disappeared 18 months before. The remains are found on the site of a travelers or gypsy caravan site and the police are convinced that George Wood, one of the camp residents is responsible, but Nikki's evidence proves otherwise.

George Wood is released by the police but he is soon found dead in his caravan. Although made to look like a suicide, it is clearly a murder. The case gets even more complicated for Nikki and the authorities when she determines that there are the remains of two victims in the field, not just one. The evidence in the George Wood murder points to someone with connections to the police. Harry Cunningham believes that the dead woman in his insurance case was likely suffering from dementia and looks to prove the cause

Following a court appearance for drunk driving, Leo is required to perform unpaid work as a punishment, assisting AJ, a community worker on a run-down,largely black-occupied housing estate in South London. AJ is hoping to divert boys away from crime by encouraging them to do sports, and, though initially dismissive of Leo as a white intruder, comes to respect him after he has saved the life of Errol, a former gang member now anxious to keep his little brother Levi out of trouble. Errol has been stabbed in the leg by members of a gang from a rival estate and Leo stops him from bleeding to death. Earlier in the week a young girl called Shana Block was stabbed to death at a funfair and her murder recorded on a mobile phone. As Shana lived on the estate police sergeant Wallace involves Leo as a go-between with the suspicious residents. Also on the scene are Harry and Nikki, the latter dating Ryan, a young Scottish paramedic she met when called to the scene of Shana's death. Before any arrests can be made, Richard Ojana, a member of a rival gang, is shot in broad daylight and nobody is willing to come forward as a witness. Believing he knows who the killers are, Errol goes off into the night, but the next day his corpse, tarred and feathered, is dumped on A.J.'s recreation ground.

The examination of the latest body from the housing estate proves it to be that of Errol Harris who was asphyxiated while being tarred and feathered. The policeman in charge of the case, DS Nick Wallace, is exasperated at the lack of physical evidence the pathologists are able to provide him as without concrete proof of who is involved in the killings, he knows they will never get a conviction. Leo Dalton thinks that the key to getting information is Errol's younger brother Levi who is actively being recruited to join the gang. Tragedy ensues however after the police question the boy. Finally at their wit's end, Leo comes up with a piece of evidence that has been available from the very beginning of the case.

The team is called in to identify the corpse of a woman whose face was surgically removed after death. Janet Mander, a Home Office anthropologist, cannot link it to similar murders but, after Nikki has reconstructed the face, Holly, a medical student on work experience with Harry,recognizes the woman as Fran Price, an investigative journalist. Pargeter, her agent, is evasive and Supt. Barker, the investigating police officer, does not help as he is obsessed with the idea that Leonid Polyak, a Russian criminal Fran helped to put behind bars, has ordered a hit on her from his prison cell. Whilst Leo gets closer to Janet, Harry is concerned when he sees Barker entering Holly's flat and later she is found murdered in her bed.

Everyone is affected by Holly Farr's murder. The pathologists find that she was tortured and beaten but died from having her throat slit. The police believe that her death is related to that of Fran Price and the recent leaks of forensic evidence to the press may have led the killer to her. Supt. Barker decides to put armed policeman to guard each of the three pathologists but Harry Cunningham, who saw Barker go into Holly's house, is suspicious of his true motives. When a prominent Russian, Oleg Kolik, seeks asylum in the UK saying he is the true target of the Russian assassins, Harry thinks that Fran Price may have been targeting him in her new book. When Leonid Polyak is murdered while being transferred between prisons, he decides it's time to put his job on the line in the pursuit of justice.

The team is called in after Mr. Stickley of the Police complaints Board feels that something is not right about an armed police raid on a house where several people were killed, including one of the officers and a mystery woman. A young Muslim called Melik has been badly wounded and lies in hospital. Mr. Stickley believes the policeman was killed by Rhys Allen, a colleague who was having an affair with the deceased's wife. Melik's sister Isra confides in Nikki that all the 'suspects' were unarmed and not terrorists and fears of a cover-up by the authorities are not helped by the aggressive attitude of Inspector Transfield, particularly when Nikki is attacked and evidence stolen from her laptop.

Harry Dalton and DI Helen Okoroafor manage to identify the dead woman from the scene of the raid - who turns out to be a DS who was working undercover and who the police refused to identify when the pathologists submitted her DNA sample to them. While DI Tranfield continues to search for the terrorist cell that he is sure is about to strike, Nikki Alexander continues to try and piece the evidence together from the scene of the raid but clearly there are pieces missing. A re-creation of the shooting shows her what happened and also identifies the only person in the right position to have shot the police officer.

Harry Cunningham investigates the death of a young Orthodox Jew. He accedes to the family's request that he not use invasive procedures in his examination and finds that the young man was savagely kicked and beaten to death. DI McKenzie has a suspect in custody but from what medical and forensic evidence Harry is able to find, with Nikki Alexander's assistance, it's obvious that the family is lying about the young man's whereabouts the night he was killed. Leo Dalton meanwhile investigates the death of a young student who died from a drug overdose. Leo is uncomfortable with what he finds, particularly that she had sex with one of the men at a party when her boyfriend was in the next room. He thinks she may have been given GHB.

With a second member of the Orthodox Jewish community dead, Harry performs a complete examination. This time, Harry does not hesitate to use all examination methods at his disposal and finds forensic evidence that clearly links a third member of the Hassidic community to both deaths. After DI MacKenzie makes the arrest however, Harry realizes he may have inadvertently contaminated the DNA evidence leading to a false result. Nikki retests all of the evidence and together they figure just who the attacker was. Leo Dalton meanwhile tries to prove that the dead student had been given GHB. He concludes that someone also tried to administer CPR.

The half-naked corpse of a twelve-year-old boy is found in his school grounds and Liam, the child in whose company he was last seen, has disappeared. Nikki is particularly involved because the school's head teacher,Noel Hopkins, is the teacher who, years earlier, encouraged her interest in science.

A severely mutilated corpse is found on a railway line, belonging to a known paedophile in his twenties, Francis Neil. Noel Hopkins is arrested, following revelations years earlier of an affair with a young pupil Nikki believes to be Francis but he is released due to insufficient evidence, though he is sacked from his job and his house torched, his saviour being Danny, father of the dead boy Michael. It is ultimately revealed that in fact Liam did not exist - he was the 20-something Francis, obsessed with Michael, and both were victims of the paedophile ring. Ultimately Nikki helps Noel to overcome prejudice and regain his job.

Stephen Harrington, a friend of Leo, is concerned that his daughter Rachel, an aid worker, has gone missing in Zambia. Leo and his colleagues fly to Africa where Rachel's corpse is discovered. It seems that she was investigating the deaths of local villagers and may have been silenced. In the absence of the local coroner, the team get involved but find that uncooperative police officers are not exclusive to Britain.

With another aid worker now dead, the pathologists are trying to piece together just what Rachel was up to. Dr. Andrews tells them that Rachel had been trying to trace the source of an infectious disease that she believed had been affecting many of the local villagers. She had originally believed that the disease was water-borne but all tests had proved negative and was therefore looking at other possible sources. Yet another death however strikes the local ex-pat community. With tensions rising, Nikki finds herself in jail and and Harry getting the cold shoulder from the local coroner.

Insurance investigator William Byfield is found gassed in his car after he has sparred with Nikki over a claim for terminally-ill suicide Sally Craven. He was also perturbed about the suspicious death of one Stephen Connelly, which leads to Leo being accused of falsifying the post mortem by William's successor, Clare Ambler. In fact Connelly's details never reached Leo and his widow, bereavement counsellor Rebecca, is not only uncooperative with Clare but is Harry's current girl-friend and overly friendly with coroner's officer David Levin. When it appears that William Byfield was murdered Harry suspects Rebecca of being involved.

Now Leo is under investigation by the police over the discrepancies in Stephen Connelly's file. He think he's found the solution when he notices similarities between the Coroner's file on Connelly and another case he had worked on. Harry is convinced that his new lover Rebecca, Connelly's widow, has nothing to do with the apparent forgeries Leo has found. He believes that the fraud is taking place at the Coroner's office and focuses on David Levin, who had access to the information. After Leo is assaulted outside his home, he is hospitalized and in a coma. On the edge of death, Nikki and Harry learn they may have a major decision to make. When the police find Leo's blood in Rebecca Connelly's home and Levin's body in the boot of her car, they are convinced they have the killer. No one however realizes the true deception that is taking place.

Left wing writer Tom Flannery rings for the emergency services when he finds his investment banker wife Bridget dead at the foot of their stairs, lying in an unnaturally large pool of blood. Both Harry and Detective Superintendant Jenkins find the death suspicious as some blood seems to have been cleaned from the wall, making a 'void', but then Jenkins dislikes Flannery's anti-police strand in his writings and she knows Bridget was insured. Nikki believes the death was an accident until Bridget's sister Muriel tells her that the first Mrs. Flannery also died after falling downstairs.

At the coroner's inquest into Bridget's death Nikki and Harry give conflicting evidence though it turns out that a young policewoman made the 'void' when she slipped on the blood and touched the wall to steady herself. Disturbed mental patient Diamanda Yannis,who had previously attacked Tom's daughter Anna, a nurse, was seen at the Flannery house, covered in blood but she dies after a fight with police. Harry has the first Mrs. Flannery exhumed, proving that someone killed her. Tom admits to Nikki it was him,during a drunken argument over his wish to marry Bridget. He also claims that he killed Bridget but Nikki believes he is shielding somebody else.Is he?

Ruth Gardiner falls to her death from a squat in a high-rise block and Leo - unlike D.I. Neill - realises that she was murdered though Neill seems reluctant to launch a public appeal. Ruth's father tells Leo she left home two years earlier, he assumes to join a cult, but had phoned recently to say she was retuning to him.Reading of the death car salesman Phil tells his girlfriend Danielle that he is an undercover cop working with Ruth - who was staking out a resident in the flats. Danielle meets with Leo, telling him Neill is corrupt and anxious to shut down Phil's operation,which is to expose sex trafficking. Phil - real name Peter Carmody - takes Alex Webb, an apparent suspect,to a caravan where he will be safe. Harry, meanwhile, discovers that a recently deceased family friend had had an affair with his mother.

Carmody goes on the run and Danielle is killed. The same man's DNA is found in her flat as on Ruth's corpse. Leo's partner Janet persuades him that Neill is not dishonest and Neill discovers that Carmody is a car salesman working with Webb. A failed police college entrant some years ago, he has persuaded his wife and mother - as well as Ruth,Danielle and Webb - he is an undercover cop though when Janet interviews his mother she says that he was a fantasist since childhood. Clearly he is a loose cannon, rubbing out those who discover his secret and must be found. Harry discovers that his father was a bully, driving his mother to having an affair.

The team attend at the apparent suicide of student Jason Renfrew at the local university. The Dean tells Leo Jason complained to her about racist bullying and he is found to have swallowed a chip containing photos of the alleged bullies, as well as having a handgun in his locker. Soon afterwards a gunman goes on the rampage, killing several people including the policeman investigating Jason's death. Nikki and Harry are trapped in a classroom with some students, one of whom, the mortally wounded Matt Frisk, was one of Jason's tormentors. Commander Somerville leads the police team who release them though it is Harry who finds the severely injured gunman. However, he fails to spot the bomb planted on campus.

Harry suspects that Scott Weston, the injured gunman, was shot by another person and it becomes obvious that two guns were used in the massacre. Scott's mother tells Dean Mears that Scott and Jason were good friends, Scott looking out for the more fragile Jason. Meanwhile Nikki is held prisoner in the deserted mortuary by unbalanced Neil Corrigan, who appears to have planned the massacre with Jason - who chickened out and killed himself - and then framed Scott. Ultimately video evidence reveals what actually happened, as well as locating the bomb.

The pathologists travel to South Africa, Nikki Alexander's childhood country. Nikki has been there for a short while and with the help of a now imprisoned official from the former regime, they've uncovered the grave of five activists who were eliminated. The problem is that they find a sixth body in the grave. Nikki is also developing feelings for the man who has hired her. Meanwhile, Harry is working with a local pathologist investigating the murder of a young girl. Leo is a bit late in arriving as he was trying to help a young girl who had requested asylum in the UK. He arrives in South Africa only to learn that the young woman has been deported.

Nikki thinks that the sixth body is that of the long missing son of her former nanny, whom she goes to visit. Harry accompanies Sara and her policeman husband as they recover the dead body of Nyasha, killed as an 'example' whilst Daya is returned to the sinister orphanage. Mandisa, the official who took Kudzai there, tells Leo it is a safe haven but it is really a brothel,trading in illegal immigrant girls with no families and the two girls found in the harbour were killed there by brutal patrons and then dumped. Leo leads the police to the brothel and the girls are saved. Nikki, however, faces a far more bitter truth as she realizes Anton has not been honest with her.

Pathologists investigate three deaths in one night in the same ward and suspect hospital staff of their murder.

In her efforts to help Naomi, Nikki believes that Silverlake was self-medicating with an untried depression cure though his widow denies it and a representative of the pill company, posing as a health inspector, tries to have Nikki taken off the case. After she is arrested for shop-lifting and feels perpetually tired, Nikki is referred to a psychiatrist who diagnoses depression. Naomi is highly supportive throughout but, at the hospital, the police make a frightening discovery which questions Naomi's motivation. Even after the real murderer is punished another death occurs, leading to closure for Nikki.

Nikki's archaeologist friend Patrick is excited when a woman's body,apparently a thousand years old,is unearthed on a Yorkshire moor. However dental records show she is a more recent murder victim and Leo,who once worked in the area,believes she is Jodie Fisher,who went missing in 1985. Three other girls were murdered and the killer,Karl Bentley,caught and jailed. Leo,unsuccessful in his efforts with Janet to make a baby and applying to adopt,reencounters Jodie's mother,old flame Carol,before visiting Bentley,who creepily says that his actions were 'out of love'. Then another woman is killed.

Janet travels to Yorkshire with Leo where she identifies the murder of the fresh victim,Kelly Summers,as being a copycat of the Bentley killings,suggesting that Bentley had an accomplice still at large. This is confirmed when Sonia Hardwick,the investigating officer,finds a letter to Bentley from a boyfriend in the original file. A television crew visits the Fosters' farm house,where Carol's husband Bill snaps,attacking a journalist. He is arrested and interviewed by Sonia regarding his relationship with Karl Bentley. Between them Sonia and Leo deduce that Bentley had a male lover responsible for the unsolved murders and that that man is Bill Fisher. They are only partly right. Harry,meanwhile,has to baby-sit the teenage son of an irresponsible old college friend.

At Hillsdon Army base,a training camp for soldiers fighting in Afghanistan,young soldier Mark Blakefield is still recovering from the death in action of his friend Danny Ferris and argues with Lieutenant Lockfield,who was having an affair with Danny's girl-friend 'Cats' Felton,a fact which Lockfield's wife Claire has also discovered. Cats' body is pulled from the river some time after she was talking to the lieutenant and Nikki suspects foul play. Then Lockfield is shot,an apparent suicide,but Harry,accompanying Inspector Suzy Harte to the base,finds from the post mortem result that the man was murdered.

Nikki links Cats to the Lockfords via her phone and,at her flat,sees photos of her with her boy-friend Danny,whose father identifies her corpse. The police catch a man skulking at her flat,Dennis Croft,a former soldier cashiered for drug peddling who says there was a cover-up over Danny's death. At the request of Danny's parents a further post mortem is carried out,ultimately proving that he was killed by 'friendly fire'.Consequently it transpires that Lockford was not seeing Cats for sex but seeing her right financially. CCTV evidence shows that Cats' death was due to a bizarre accident but who killed the young lieutenant and why?

Harry is in Budapest with Anna Sandor, a lawyer committed to women's rights who wants him to perform a second autopsy on Sofi, a pregnant Romanian prostitute drowned in the Danube. Anna disbelieves the official version that Sofi killed herself but the body is quickly cremated and Anna is murdered. Harry is pursued by the gangsters who killed her, hiding out with street dweller Janos, who tells him not to trust the police. Leo answers Harry's distress call and flies out but Anna's doctor father believes Harry murdered her and detective Orban tells Leo Anna was pregnant by Harry. Harry breaks into Anna's office, finding links to a brothel run by the same tattooed men who pursued him. He and Janos flee but the men shoot them. Leo suspects police duplicity in the gang's ability to locate Harry so quickly.

Nikki flies to Budapest and is called to a secret meeting with Leo to avoid Orban. Harry appears, having faked his death to pursue his enquiries. From another prostitute Marina he learns that the gang use the girls to produce babies for influential people who, for various reasons, cannot have children of their own. If the girls are HIV positive like Sofi, they are killed, a fact that Anna had uncovered. Harry approaches Anna's father who says he knew what was happening but wanted to shield Anna from it, before dropping another bombshell. With the British ambassador and other dignitaries involved in the plot, the pathologists have to trust Orban if they are to bring an end to the racket.

Nikki and Harry are called to the Dutch Embassy in the wake of a gunman killing three people,including police constable Barlow and the brother of ambassador Van Buren,though the latter officially died three years earlier. Van Buren's son Jacob went missing fifteen years earlier and now his grandson Jack is missing, Jack's mother Klara and young policeman Whitehead being among the wounded. Curiously the CCTV cameras were switched off at the time of the shooting but,recovering in hospital,Klara claims the murderer was Jacob. The news coverage has a strange effect on telephonist Mary Olivant,who is found hanged,though Leo finds the death suspicious. He is also wary when another pathologist,Sabiston,whom he once trained,is called in to carry out the post mortems at the ambassador's request.

Mary Olivant turns out to have been the Van Buren's nanny at the time of Jacob's disappearance and a body unearthed near to where her corpse was found is identified as that of the little boy. Diederick Van Buren had been paying her thousands for years but she had recently seen Klara and told her the true fate of her brother. The so-called bodyguard was actually Diederick,allegedly working for MI6,and the pathologist who pronounced him dead three years earlier was Sabiston,working with Superintendant Mansfield in a cover-up on behalf of the embassy. Harry finds Jack,who has gone into hiding and who saw all that happened on the night of the shooting,for which reason he is protecting the killer.

Following the suicide of colleague Lizzie Fraser, who he believes was scapegoated by police for a wrong decision, Leo comes to work in an angry, bitter mood. DI Connie James brings Leo, Harry and Nikki in following the brutal slaying of ex-SAS soldier Mick Francis, his daughter Jessie, and her young son Luke at their farm shop during a robbery. Harry establishes a good rapport with the pregnant Connie but then Superintendent Byrne links the murders to that of Lizzie's sister Mary twelve years earlier and to several other unsolved murders in the intervening years. Byrne believes the killer is a drug-addicted woman known as the Wraith, working with a male accomplice. However unknown to him a hooded white boy who was at the shop would seem to fit the bill.

An eye witness account and identification of a car links a youth called Lee Ness to the farm shop murders but he claims not to know the Wraith. Tom Byrne,recently widowed,and Nikki,who has just lost her father,develop a rapport whilst interviewing the parents of another supposed victim of the Wraith,who have their own views on the murderer's identity. A discrepancy in the findings of the Wraith's DNA at different crime scenes leads Harry to take samples from a rival laboratory. The result reveals an elaborately plotted revenge scenario to punish the police for the deaths of Mary and Lizzie.

When Nikki sees barefoot teen-ager Shannon Kelly run over by a car whilst fleeing somebody she sits with her until the ambulance arrives and later visits her in hospital,where it is clear she is frightened of a man. DS Masood tells Nikki Shannon has been sexually abused and suspects Abdul,her estranged stepfather. Shannon turns up at Nikki's and reluctantly agrees to go back to hospital. Meanwhile a gang of young Asian men are picking up and grooming white school-girls for the sex trade. They already have Shannon's friend Amy and go after two more,Hannah and Lauren. The pathologists investigate two seemingly unrelated cases - the remains of a young girl found in discarded airport luggage and a heavily tattooed man,John Dear,who died of toxic poisoning. Then a third corpse is found - that of Amy.

Through a DNA link the pathologists find that John Dear was a client of unwilling child prostitutes Shannon and the deceased Amy whilst the suitcase victim is also identified. Nikki visits Shannon in hospital and learns about the gang of abductors but the young girl is too scared to name names. Through CCTV DS Masood gets the car registration number of a visitor to Shannon and arrives at a taxi firm where Salman,a somewhat reluctant and kind-hearted gang member, works. Salman helps Hannah and Lauren escape but is killed when his taxi crashes. The three girls are returned home but will not speak about their ordeal and,with Abdul swearing revenge, Nikki must help DS Masood resolve matters. The case closed Harry announces that he is leaving to take up a professorship in New York.

Leo gives evidence at a custody hearing in the wake of a child's death,his opinion over-ruling that of Dr Helen Karamides,which annoys her former pupil Nikki,who sees Helen as the victim of the male establishment and cannot believe the accusation that Helen is retaining tissue samples from past cases. Nikki is also approached by Andy Farmer. His mother Annie was the appropriate adult at the interview with serial killer Arnold Mears,who now directs Annie to the sites of his victims' remains where she collects their bones. Andy wants Nikki to help identify them. Nikki also discovers that Helen had a professional involvement with Mears.

Leo feels guilty when Helen kills herself,leaving an explanation on Camcorder that she took the tissues to further scientific research. Aware that Mears killed more women than he was imprisoned for, Leo tells the police about the arrangement with Annie,scaring Andy, who believes that Mears will have his mother murdered for the breach of trust. It is also revealed that Annie believes her daughter was one of Mears' victims,hence her involvement with him. When Annie disappears Nikki visits Mears,who agrees to tell her about all his other victims. He appears to have won his mind game with her but his possessiveness over his copy of 'Paradise Lost' and Nikki's chance remark about an elderly lady she met who knew Mears yield results.

Harry's work colleague Justine Thompson is murdered in her house with her daughter Gemma whilst her stepson Charlie, also attacked, lies in a coma. Baby daughter Ellie, however, is unharmed. Husband Stuart is prime suspect but he has an alibi and his grief seems genuine. The post mortem shows that Gemma was pregnant and the team learns that Justine once needed a restraining order against Stuart's brother Kevin, who was obsessed with her. Mrs Barron, the lady from next door who found the bodies, finds evidence on her son Joel's computer that Gemma and Charlie were lovers as Joel rides off to see Kevin.

After Kevin dies in a motorcycle crash Harry is surprised to see Joel keeping a vigil by Charlie's hospital bed. Whilst denying murder Joel professes that he loved Gemma was shocked that she was sleeping with Charlie. Stuart's initial alibi breaks down when CCTV footage shows Kevin, not him, at the hotel in question but he admits to an affair with Mrs Barron. The murderer is eventually exposed after a shocking betrayal is revealed, leading to an horrific reaction.

Prison inspector Rachel Kruger is murdered,along with young Nick Owen,a man she was visiting,whose computer is stolen.Inspector Bridges tells Leo she reckons Rachel's husband Peter killed his wife and her suspected lover but Peter claims that Rachel was in danger because she was investigating sinister events at Redhill prison,particularly the mysterious death of convict James Wade,and Leo believes him. The team joins the police investigation of Redhill,where governor Cairns is less than helpful and Rachel's original source,Dr Ross,too scared to speak out. But, unbeknown to the pathologists, Bridges knows far more than she is letting on.

When prison officer Ellis Roberts and convict Benjamin Johnson are killed after a supposed cell fight Leo is suspicious of corrupt officer Kessler,whose evidence about the fight does not ring true and is found to have fathered a child with Andrea Bridges before he left the police under a cloud. Nikki persuades Bridges to confess that she covered for Kessler in the past but,despite Kessler visiting Leo to threaten him,there is doubt that he murdered James Wade and the prison inspectors Kruger and Owen. The eventual discovery of the truth spells bitterness for both Leo,ending his relationship with Janet,and Harry.

Leo is called in by his old college friend,psychiatrist Sean Delaney,now a cancer-stricken alcoholic. Sean was treating inspirational,deeply religious teenager Eve Gilston,who felt neglected by her family ,and the verdict of whose death,alone in bed,apparently of arrhythmic death syndrome Sean does not believe. Accompanied by down-to-earth sergeant Brooks Leo interviews Eve's parents,lapsed Catholics Beth and Tony,wondering if the family is prone to the rare heart condition Long QT Syndrome,though John,their blind younger son refuses to be tested. Sean tells Leo that,at their last session, Eve believed that she was possessed by evil and soon afterwards Leo and sergeant Brooks find evidence that a priest performed an exorcism on her.

Shocked by the news of the exorcism Sean joins Leo in visiting Father Jacobs though he tells them that he did not perform the exorcism and Nikki tracks down the nun,Sister Landsley,who did so,only to find she has killed herself. Leo believes the trauma of the exorcism triggered Eve's death but then he learns from Beth how Eve thought that she was possessed after passing on the measles which blinded him to John when they were younger. With the knowledge that his grandmother killed herself John believes that possession runs in the family and now he is host to the demons, leading to a further exorcism.

Confectionery magnate John Briggs, head of an ailing empire and at odds with union leader Kenny Barber, is found dead of an apparent heart attack in a hotel bedroom. He was about to sell his company to millionaire Emmett Schwartzman. His sole heir is long estranged daughter Geraldine, to the chagrin of his brother Phillip, whom Geraldine appoints as company director. Young police pathologist Jack Hodgson claims Briggs was murdered, believing he had been with a prostitute, and is sufficiently persuasive that Leo recruits him to replace Harry, now working in New York. Briggs' right hand man Trenter pays off escort Deanna Collier, who is actually Geraldine's daughter and had just tracked Briggs down. Geraldine gives Deanna a charm bracelet but soon afterwards the girl is murdered.

As Nikki discovers that Deanna was not Geraldine's daughter but an opportunist out to fleece Briggs, Schwartzman decides against buying the confectionery firm. Interviewd by DS Gold in Nikki's presence Geraldine explains that she was raped by Phillip Briggs as a teenager and her baby given away. John Briggs' legal adviser Annette, who found Deanna, expresses unease to Tranter about the deception and is later found murdered. Geraldine is arrested but the pathologists, aided by Jack's wheelchair-bound mentor Clarissa, uncover the truth though the killer never makes it to court. Geraldine is, however, reunited with her real daughter.

Leo attempts to help Mark Benson,whose wife Shona was imprisoned for killing their baby and begins to spot discrepancies in the expert witnesses at the trial. Petra Smith is abducted and imprisoned in a remote farm building at the same time as two women's corpses are discovered in a basement. The officer in charge, Chrissie Reid, once has an affair with Jack until he accused her of corruption in order to get an arrest. The two women have been injected with a toxic substance and Chrissie and Nikki visit the factory that makes it. The suspicious actions of scientist Lucas Ballinger cause them to follow him to the hide-out where a man called Hearns has imprisoned Petra and is about to inject her though Lucas is scared as he had not realised that anybody would die. Hearns kills him and sets fire to the building and Chrissie pursues him, leaving Nikki inside the burning building.

Nikki escapes the burning building but Petra dies and Leo's examination shows she was injected with anthrax. Jack identifies one of the basement victims,also injected,as being Lucas Ballinger's wife and Nikki surprises him at the scene of the murders though he flees. He goes after Hearns and later Chrissie finds Roper,who was the accomplice in taking the virus out of Ballinger's workplace, dead. The team must locate Ballinger and find out why he allowed his wife to be a victim as well as stopping him from committing a terrible revenge which could endanger thousands of lives. Leo meanwhile successfully gets Shona's conviction overturned.

Pub landlord Roly Henderson is accused of stabbing to death his wife Joanne in her sleep and cutting off her little finger. DI Kate Warren is anxious to convict,under pressure from her father a deputy chief constable,to further her career but Clarissa and Nikki find proof of Roly's innocence and his little daughter Emma recalls seeing a strange man in the pub. Nikki visits Simon Marshall,convicted of killing his wife Eleanor four years earlier as her finger was also chopped off after death. Simon tells Nikki his wife was murdered by a biker and Nikki and Jack find evidence to support his story. Nikki believes this man killed Joanne,Eleanor and a third victim,Imogen Lane,who married the older policeman Alan who rescued her from her pimp when she was a teen-aged prostitute. Alan was convicted of his wife's death but is now released. Imogen's mother Edith hated Alaan,believing he killed her husband as well as her daughter,whom she feared he would harm. Edith is unaware that she is being shadowed by Janice Masters,a single parent who also has a little finger missing.

Jack discovers that Kate,under pressure from her corrupt father,has tampered with evidence to incriminate Roly Henderson and demands she accept Nikki's opinion that Alan Lane killed all three victims. They visit Anne Percival,the retired officer who sent lane down even though Imogen's body was never found - in the event because,thanks to Anne,she was given a new identity as Janice Masters. Nikki finds out that Lane has killed nine women who all has histories of domestic turbulence so that their husbands were blamed. After Anne has fatally tried searching Lane's house the team must stop him before he can get to Janice.

The body of young Colin Connor is found in an attic at a former hospital now marked for residential development. He had been stealing metal but was locked in the attic by his accomplice who then fled. The culprit seems to be Derren Blackburn whose father lies for him when D.I. Cherry visits with Jack. At the same time, Leo is asked by distraught father Tom Hancock to conduct a post mortem on his son Peter, who, Tom is convinced, died because of electrical towers outside his window. Leo is surprised to find that Peter and Colin had an identical kind of kidney dysfunction. James Embleton, a government minister who begins dating Nikki, is in charge of the hospital conversion, and is visited by the sinister David Loader, who warns him of Leo's investigation into Colin's death. Leo and Jack look for proof of toxicity at a farm near the hospital, but are evicted by the army. Leo contacts George Ryder, who owned the farm, and they agree to meet at the hospital as George has an important revelation, but tragedy intervenes.

After Darren is killed trying to escape, his father tells Leo of the boy's recent personality change, and examination of his body shows he had Fanconi's Syndrome like Colin and Peter. Nikki tells James that Leo suspects a conspiracy, especially after George's daughter has spoken of the haste with which the family was moved from the farm and the poor compensation they received. James now comes to see that his father, Sir William, and his henchman Loader - who Jack proves killed George Ryder - are involved in a cover up. After being falsely discredited and suspended from work, Leo joins Tom to investigate the woods near the farm and hospital and discover what the cover up had been trying to hide. As Nikki asks James how much he knew, Tom sets out for revenge.

The team goes to Afghanistan at the request of sergeant Scott Lambert to see if human remains found at a charity water supply project are those of his brother Daniel,missing for five years and presumed murdered by the Taliban. On arrival in the country they encounter a road block and land mine and Jack's mistrust of the army does not go down well with ex-military man Sean,who heads the private security force. Nikki finds some bones but her examination is interrupted by a Taliban attack,repulsed by Scott's men. Project leader Fawzia believes it was motivated by opposition to Western influences,exacerbated by the pathologists' arrival. Fawzia shows Leo a ruined building where Daniel was apparently imprisoned and Jack finds proof of his being shot in the back of the head. Nikki however worries herself over the treatment of the Taliban prisoners,who include an English fanatic,after one of them is killed by Sean and his death made to resemble suicide.

The team continue to investigate the death of Daniel Lambert and make a significant discovery that changes the whole situation.

As Leo's replacement Thomas Chamberlain arrives Nikki investigates the murders of Rachel Freedman, shot in the head, and her little autistic son Nathan, who was poisoned. Nikki rejects policewoman Anne Burchett's theory that Rachel killed them both but is perturbed when an impostor, claiming to be Rachel's sister, visits the morgue. At the same time the disfigured corpse of Eva Liron is discovered, killed with the same poison as Nathan. She had been the nanny to French hot shot footballer Isaac Dreyfus and was planning to blackmail him over a sex tape of them both. Jewish Isaac is a controversial figure due to his anti-Muslim sentiments but he denies ant part in the murders. Then another victim, Isaac's agent Mousa, is discovered dead.

Isaac is arrested but club bosses deny knowledge of the sex tape whilst Rachel's widower Adam tells the police that Eva Liron had been Nathan's nanny but had left suddenly. With Mousa shot by the same gun as Rachel ambitious Inspector Leighton assumes that he was delivering the blackmail hush money and was killed by Isaac, whom he wants to nail, though the pathologists will not assist in any stitch-up. Then Clarissa discovers that Adam and Isaac both donated money to Israel and the motive appears to be that they were targeted by anti-Zionist terrorists after Eva had picked them out. But who is the mystery woman posing as Rachel's sister and who perpetrated the murders? The pathologists assist the police in finding out.

Forensic evidence given by Nikki contributes to the release on appeal of disturbed ex-soldier David Bennetto, charged with murdering two gay boys, one of whom he had sex with. DI Rachel Klein is not convinced of David's innocence , especially when a rent boy calling himself Byron Lee is shot dead and David's car is caught on CCTV near the murder scene. The fact that Nikki is dating Bennetto's solicitor Greg Walker makes her partial in the inspector's eyes and she is removed from the case. On the night that yet another gay youngster Charlie Masham is also shot Greg, on a date with Nikki, gets a frantic phone call from Bennetto and they go to his flat where he points a gun at them after he discovers Nikki has found his kitbag containing the murder weapons

The police surround the flat but David hands the gun over to Greg, explaining that it was his father's gun, which he had found and wanted to get rid of. Nikki is verbally abused by Charlie's father and DI Klein wants her suspended but Clarissa and Jack discover that the gun found by David did not kill Charlie and nor could he have killed Byron Lee. The pathologists work out that the real serial killer had an alarming insight into David Bennetto's background and their motive was not sexual but obsessed with having power over others. Circumstances also end Nikki's involvement with Greg Walker.

Following the discovery of a young woman's corpse in a forest Nikki and Jack travel to Scotland to assist DS Jason Ross, who mistrusts local pathologist Dr Jenkins. Prime suspect is hunter and gunsmith Niall Wallace but he is eliminated from enquiries. A clue leads to the Manhattan strip club, owned by Stella Nelson, who identifies the dead girl as Caitlin, who apparently gave no surname. Another dancer Amy tells Jack that Caitlin disappeared after getting into a car with a stranger but the local police, obnoxious DS MacNeil and DI Laing were not interested when she reported Caitlin missing. Five more female corpses are discovered in the forest, denoting a serial killer. When news of the murders becomes public Sarah O'Keefe tells her boyfriend Steve Boyd that some years earlier she escaped a rapist and would-be killer in the same forest but, as she goes to tell the police, she is abducted again.

Nikki and Jack , joined by the apparently decent Dr Jenkins, unearth more bodies, leading to Niall being rearrested. Steve Boyd reports girlfriend Sarah missing, revealing to Jack what she had told him about her previous ordeal, whilst Jason Ross admits to Nikki he called her in because he felt that in the past Jenkins had colluded with Mac Neil and Laing to falsify evidence. In fact Jenkins confesses to Nikki that he had been forced to lie because Laing spent most of his time covering for loose cannon MacNeil and needed his help. The pathologists return to the Manhattan and learn that almost all the victims had worked there, including, very briefly, Sarah. As a result Stella makes a phone call to Laing regarding her son Jerome. Laing finally confesses to Nikki, Jack and DS Ross about his relationship with Stella, which consequently leads to them finding Sarah and identifying the serial killer.

Nikki and Jack assist DS Sally Kirchner in identifying teen-aged Alice Preston, who was murdered and her baby taken live from her womb. DNA identifies the father as married Simon Turner, who admits to a one night stand with Alice but claims he never saw her after giving her money for an abortion. Alice was a drug runner, sharing a flat with two other drug dealers, Mark Blakefield, who is also murdered, and Nuri Kavur, who turns out to be the informant for DI John Brooke of the drugs squad. Nuri believes his uncle, Turkish gangster Bekir Humadi, has slain the others after a consignment went missing and fears for his own life. Brooke arrests Humadi for the slayings, after finding evidence at the flat but Jack believes he is actually framing the Turk.

As Nikki tries to explain to Alice's father of her drug involvement Martin Carrisford, the witness to Alice's murder, is also slain. Humadi threatens Nuri to locate the missing drugs though he denies killing Alice. Nuri is shocked to find that Brooke and his wife have Alice's baby . Brooke assures Nuri he does not know where the drugs are but Nuri steals the baby, taking it to Humadi to use as bargaining power with Brooke for the drugs or their value. Having accidentally discovered the drugs Brooke goes to broker a deal with Humadi, sacrificing Nuri, who is killed. Brooke is prepared to arrest Humadi but Jack works out who really murdered Alice and Carrisford and why.

The body of teenager Katie Bowman is found dumped in an open grave. DI Carter suspects Ryan Kelvin, boyfriend of Lizzie Kennedy, whose daughter Hannah was Katie's best friend. He argued with the deceased girl the day she died and has no alibi. Ryan is also Jack's half-brother, whom he has not seen since he was forced to testify against him in a court case some years earlier. To avoid a clash of interests Thomas brings in pathologist Helen Ferguson, suspending Jack. Jack however does his own sleuthing. showing Carter that Katie had been to a club where she met Christy Nash, a married doctor with whom she had sex. Nash's wife gives him a false alibi to protect their daughter but declares her intention to divorce him. Ryan is bailed and moves in with Jack, who now doubts his brother's innocence whilst Hannah is killed after confronting Dr Nash.

Things look bad for Ryan when Lizzie tells Carter that he rowed with Hannah a couple of hours before she died as a result of which he makes an unsuccessful suicide bid. Nikki is surprised at the lengths Jack will go to exonerate his brother until he tells her that was the assailant in the criminal case and Ryan took the blame to save his career. Jack pursues Christy, who admits to falling for Katie, unaware that she was a minor but some while afterwards Jack is the victim of a hit and run, which he survives. Ultimately the killer proves to be protecting a professional, rather than a personal, interest though Ryan, cleared of the murders, is not wholly innocent of another crime.

Three people, the Lakhanis, an Indian couple, and an employee are shot dead by a long range sniper on a garage forecourt - a seemingly motiveless crime. Ten miles away another victim, profoundly deaf Hannah Smithson, is also shot, though her boyfriend's brother Chris, targeted with her, survives but is unable to help with any information. Inspector Jane De Freitas, on the rebound from an affair with colleague Robert Drake, calls in the pathology team but with the sniper at large and shooting indiscriminately Thomas is concerned for ex-wife Julia and their daughter Rosie, now living with former drug user Conrad Devenish. After a fifth victim, Martin Cross,a charity worker at a school is shot the killer rings Jane to tell her that he is unstoppable.

Whilst the sniper claims another body, a French lorry driver, there are fears that he may next target a school and Thomas rushes to ensure his daughter's safety. Drake calls a public meeting to pass on police progress, whereat Martin Cross's brother Ian praises him. Nikki however believes that Cross may have been the only intended victim with the others slaughtered to give the impression of a serial killer. Jack learns that Cross regularly assaulted his wife and teen-age son Craig, who hated his father, and Craig has bullets in his bedroom. Nikki and Jane now feel that Craig was working in tandem with the murderer but when the sniper strikes again Craig is standing next to the victim. They start to wonder if Martin Cross was the only person the sniper wanted out of the way and how many were working with the killer.

Nikki and Jack are called to a tube station where a homeless ex-soldier has fallen under the wheels of a subway train. Leaving the station hotel receptionist Lana Sutherland meets another homeless man, Owen Hanmore, whom she invites to stay with her, becoming his lover. Meanwhile a series of murders occurs with no visible link, beyond the fact that all the victims had used the same tube station.

Whilst fibres under the nails of the latest victim provide a link the the St Jude's homeless hostel Lana is interviewed as a formality and states that Owen Hanmore was outside the tube station at the time of the first death and must thus be innocent. Clarissa, however, finds evidence of Lana's prints on the victim's phone and Lana and Hanmore are both increasingly under suspicion as they locate Lana's child and attempt to kidnap him. The child will provide a link to the murders whilst Nikki helps Luke to come to terms with his own past.

Little Lizzie Craddock goes missing after social worker Louise Dillon has unsuccessfully applied for a care order given her father Johnny's violence. At the same time suspected paedophile Dale Barge is murdered and pictures of Lizzie are found at his flat. Young Kevin Garvey leaves care but goes to stay with his grandparents, rather than inadequate mother Niamh and stepfather Daniel, whom he blames for himself and his sisters going into care. Then Daniel is found dead.

Johnny is arrested for Dale Barge's murder but Lizzie is still missing. Evidence suggests that Kevin was present at the car where his step-father was murdered but he seems unaware of the death when he asks his sisters to run away with him and receives some shocking news from them. Lizzie's story ends well but after Kevin's grandfather Sean Patrick is also killed a terrible family secret is exposed, leading to the solution of the murders.

A shootout at a City hotel leaves young Ukrainian nanny Sofia Teplov dead, along with an unknown hitman. The Russian oligarch target Maksim Bazhanov narrowly escapes.

A young woman working for the Doshi property moguls, Amy Greenwood, is found dead in Maksim Bazhanov's apartment, and Maksim is discovered to have been in a relationship with Yasmin Doshi.

Whilst cage-fighting Jack takes on young Dean Fallon, drug dealer and son of career criminal Terry Fallon. When policeman Sam Honeywell's corpse is discovered in his burnt out car Dean is the main suspect after Honeywell had arrested him but is released for lack of evidence. Sam's colleague Carl Parry is then arrested when it is made known that Carl's wife Kate was having an affair with the dead man. After Dean has fallen out with his friend Jason Simons over Dean's girlfriend Tess Hughes Tess finds drugs hidden in her father Stan's garage, which she takes to Jason. Soon afterwards he too is killed.

Following Simons' death he is revealed to have been an undercover policeman infiltrating the Fallons' drug dealing empire. Tess questions her father and is shocked to learn that he is part of the gang before Stan gets a visit from Fallon's lawyer telling him to say nothing. There will be another death and a shoot-out before the killer is finally exposed.

The apparent suicide of a DJ leads Nikki to question her judgement on a similar case from her past. She fears the killings could be personal to her, but if that is the case who can she trust?

Nikki is arrested when a former colleague she came to blows with is murdered. Tony fears that his son David may be involved in the killings, but Nikki has her suspicions about someone once close to her.

When a young British Muslim returns to the UK in secret it is thought she may be connected with drug smuggling, but when a leading anti-fundamentalist Muslim is murdered something more sinister is feared.

As the team try to track down Sarah Begovic, before she and her extremist compatriots can strike again, it becomes clear that she may not be the one who shot Ryman.

When an ex-convict is found murdered in his home suspicion falls on a recently released child killer. Both men are clients of forensic psychologist Sasha Blackburn, whose work with the men is called into question.

As further victims are murdered the Lyle team revisit a 15-year-old case that leads them to believe that Paul is not who he says he is. The team turn to Sasha for help but has her viewpoint been compromised?

The accidental fatal shooting of a Polish teenager during an armed police operation prompts a series of murders linking Turkish gangsters, the grieving family and a fractured firearms unit.

When the body of an armed police officer is found, the team join the search for the killer. Jack discovers a link to London's gun trade and puts himself in danger to discover the truth about the death of the young Pole.

The team investigate the systematic shooting of a family picnicking beside a river. The case stirs memories of the death of a young woman beside that same river 10 years earlier.

As DCI Butcher moves closer to making an arrest, the team continue to pursue their own lines of inquiry. Amy's past begins to catch up with her and converge with the team's investigation.

The team assists DI Paul Renick following the assumed suicide of Jamal Al Sham and discover that he was murdered and was a people smuggler, blamed by Varkey Khoury, head of a family of Syrian refugees, for killing his wife. Varkey's 15 year old daughter Akka approaches Nikki for news of her mother, leading to Nikki sheltering her whilst the police haul in another young woman Tamara as a likely killer. At the refuge camp in Calais apparent altruist Yusuf Hamed assists 12 year old Sosa to come to England whilst Kalil Aziz, an associate of Sham, is also murdered and the police and pathologists make a grim discovery in an English forest.

The pathologists join the police in removing the corpses of the refugees who suffocated in the locked van and find a possible clue in phone messages sent by the dying victims. Whilst a customs officer due for retirement is suspected of allowing the people smuggling the team establish that the culprit took money from the relatives of the migrants he then left to die, Akka's mother among them. Yusuf rescues another batch of refugees from a second locked van, escaping with Sosa before the police arrive but the real clue surfaces via a Syrian charity to which the killer donated the victims' monies.

When teacher Lucy Chatham is abducted Nikki and Jack help police officers Andy Steemson and Karen Wretzy investigate the circumstances of her disappearance whilst Thomas assists abrasive DS Maureen Steele when ex-addict Tina Lunt is murdered. Doctor's daughter Jessica Timpson saw a car outside her house near the spot where Lucy was taken and her parents Nick and Ellie fear it may belong to Ellie's brother Alec Porter. Tina's death points to criminal boyfriend Wesley Beale whilst Lucy's sister's boyfriend Jasper Lampton is the key suspect when Lucy, his secret lover, is found dead. Forensic evidence suggests that both women were killed by the same man. Then Beale is murdered.

Ex-drug user Jasper is hauled in by Steemson for killing Beale, who had been his supplier but released again whilst Ellie confides her fear to Nick that Jessica is covering for Alec, whom he believes to be the murderer. Then Clarissa finds a link between Alec and a twenty year old crime in Brighton for which he was acquitted. As a result he goes on the run and Ellie finds herself in danger from an unexpected source before the multiple killer is caught.

Lorna Katz's body is pulled from the Thames and DI Heather Ashton hauls in Kieran Vale, the boyfriend Lorna dumped but wanted to get back with. Another suspect is houseboat-dweller Aaron Logan, a boy who dated both Lorna and Ruth Tresize, a girl who disappeared three years earlier. The discovery of Lorna brings her estranged parents Ali and Chris to seek answers from Nikki. Following a clue on Lorna's phone Kieran does some sleuthing of his own, resulting in his murder, whilst Aaron, the prime suspect, goes on the run but is sought out by Ali, who attacks him.

Ali is arrested for stabbing Aaron, who discharges himself from intensive care aided by brother Ben and his wife Sarah. Visiting Ali in custody DI Ashton suggests that Chris killed Ruth and gets an angry response whilst illegal immigrant Stella Duffour is interviewed as the person who reported Lorna's death, resulting in her being threatened. The pathologists pick up on the evidence that sent Kieran to embark upon his fatal mission and locate the spot where Ruth was killed. An unusual discovery by Clarissa is also instrumental in catching the murderer and closing the case.

Clarrisa's husband Max is brought to the Lyell Centre to help crack a case.

Becky's father Stuart is arrested following the discovery of footage on Frankie's phone of Becky having reluctant sex with both the dead boys. However Clarissa spots Becky's devoted flat-mate Paul watching them surreptitiously though his DNA is not found at either murder site and he has an alibi for both crimes. Then headmaster Clive Maitland is stabbed to death, following a run-in with two ex-pupils though his murder seems unrelated to the others. When Max is recalled he establishes a lethal link between two parties with no obvious link.

When Luisa Herrera, a former intern at the Lyell Centre, is killed in a car-jacking in her native Mexico Nikki arrives for the funeral, only to find that the body in the coffin is not Luisa's. She seeks out Luisa's boss, Dr Eva Vasquez, who runs a charitable hospital, also a centre for a dedicated band who search for families abducted by drug cartels as the police are too afraid to. Luisa was one of that group. Jack flies out to assist Nikki look for her friend, unearthing the bodies of several torture victims but chief suspect El Buitre refuses to give any information even when Nikki withholds his medication. Eva's son Ernesto is also kidnapped and Eva and Nikki, following a tip-off, go to find him. However Jack discovers Eva's car with Eva inside but no Nikki.

Frantic to find Nikki, who has been buried alive, Jack gets a mysterious phone call allowing him to ring Nikki and another call demanding a ransom and the release of cartel member El Buitre but the exchange goes wrong. Helped by Luisa's lover Gustavo Jack is able to locate and free other abductees from their underground prison, including Luisa herself and Eva's son Ernesto but Nikki is not with them. Ultimately Nikki draws on the lessons she learned from former mentor Leo to try and free herself whilst Jack discovers that she has been the victim of a desperate arrangement.

Thomas and Jack are surprised to see Nikki back at The Lyell, the disappearance of her friend Sally forces her to face her back after her harrowing experience in Mexico.

The team unearth a tragic triple killing, and there is more sorrow for Nikki.

Pregnant Karen Sawyers is murdered and her blood-stained husband Pete found wandering the streets but DI Naomi Silva turns her attention to Karen's lover, Adam Hayes, who was treating her at his clinic and had arranged for her to have a termination. Then Adam is also found dead. Clarissa finds evidence that Karen was being blackmailed with threats of Pete getting her medical records. This leads Naomi and Nikki to hospital head Simon Laing, who tells them a computer hacker calling himself Splinter stole patients' files though Simon kept it quiet for fear of tarnishing the hospital's reputation. Meanwhile barrister Jason Farrell is viciously attacked and left to die.

With Jason in a coma the police, given his hospital attendance, assume he was Splinter's latest victim though he was not robbed. A known hacker Gary Brockham is arrested and admits to selling hospital files on the dark web whilst Laing must admit his use of a questionable computer system company. He too is killed before a secret from the past resolves the case.

After US ambassador Jonathan Kraft has given a television interview his aide Ryan Reed is shot dead. The embassy's deputy chief Matt Garcia discovers the married Reed had been having an affair with colleague Terry Lefoe but she has an alibi and terrorism is suspected when Matt receives a parcel bomb which is intercepted. Then Helen Vine, a respected American pathologist who, like Ryan,, had spent time in Africa, is also murdered. Confused psychiatric patient Fergus Weir is released to the care of his sister Ella but disappears and CCTV shows him to have been at Helen's hotel, leading to his arrest and confession. Nikki spends the night with Matt but has a rude awakening.

Matt is found alive after his abduction but admits that the kidnapper wanted information about an incident that happened in Africa when Helen and Ryan were there. All of the victims, including another in Florida, were murdered in the style of assassinated American presidents but Fergus has an alibi for them all though Matt learns that he has information which identify the murderer. Now the police and the pathologists must work together before Fergus is also killed.

Kevin McDowd, a boy with behavioural problems, is restrained from escaping Kingscote Bows, his residential care home whilst, a few miles away, his mother Jackie dies in a car crash, having ingested an excess of anti-depressant pills. Nikki believes she was unlawfully killed and evidence points to Kevin being the culprit. Kevin goes on the run with fellow resident Serena, who, to the horror of care assistant Tilly Maddox, is being sexually abused by deputy manager Conor Flannery, but they are cornered by the police with unfortunate results.

Examining Kevin's corpse Nikki is puzzled by stun marks on the body and the fact that Jackie had set up a camera in his room. Thomas is also curious regarding two other mysterious deaths, one at Kingscote Bows, the other at the Pleasant Manor care home, where both were regularly visited by Dr Kahari. When Serena goes missing and Tilly is found dead after threatening to expose Flannery Clarissa books herself into Pleasant Manor to investigate herself,. She unmasks the killers but needs to be rescued by Jack when she puts herself I danger.

On Christmas day the team is called to the home of haulage company owner Andy McMorris to find three corpses and Andy disappeared. Sniper shots ring out, wounding DI Gibbs and McMorris's blooded daughter Mel tells Nikki her father shot at her and her horse. A large number of weapons are found in the home suggesting illegal gun importation whilst the diary of Mel's sister Stevie expresses hatred for her father and his estranged wife Zoe. DCI Cooke, a friend of the family assumes the case but appears to be hiding something and Clarissa discovers that the 999 call reporting the shots was made over twenty miles away.

As the three corpses are identified Vernon Rye, a friend of Andy's father Martin, one of the victims, is pulled in after admitting to a fight with him but Mel, recovering in hospital, tells Zoe and Nikki she heard Andy and Martin rowing before shots rang out. Zoe's sister Jackie is another suspect having had an affair with Andy, but claims she left the house before the murders. The discovery of a missing lorry full of guns and another body proves Andy's criminal activities and reveals who made the phone call. Cooke thinks he has found the killer but the pathologists' evidence proves otherwise.

Nikki and the Lyell unit are called in to investigate an attack against a transgender man.

A mistake has been been made during the course of the investigation, and Thomas is targeted as a scapegoat.

After a teenager is killed in an explosion the drug ring to which it is linked uncovers the dark underbelly of the community in which it has been operating.

Noah is put on a collision course with the criminals behind the drugs.

The Lyell team are summoned to a waste dump in Brighton where a body part has been found. The search is on to recover the other remains.

The team must painstakingly piece together the evidence and unearth the connections between a diverse range of suspects.

A shocking incident on a suburban street brings back painful memories for Jack, forcing him to revisit his past.

During the team's search for the killer, Jack works alongside an old friend from Northern Ireland, and they uncover a complex conflict.

Nikki is humiliated in court when a barrister accuses her of making a serious error in the case of a policeman who may or may not have been murdered.

When Thomas sides against her findings on a controversial case, Nikki suspects foul play and takes steps to prove her theory.

A private jet crashes into woodland outside London. Among the passengers is a former U.S. Ambassador. Thomas investigates the apparent suicide of a successful businessman, finding unexpected connections to the plane crash.

With an explosion or engine failure ruled out of causing the crash, suspicion falls on the Deadhead - a non-flying pilot hitching a ride when his intended flight was cancelled. Then a connection is made to a sinister online forum.

When the body of a teenager is found in a field near the village where he lived the team must determine if the killer is a stranger or a local.

The team question police methods as Thomas discovers evidence challenging the time of death. Ashby seems more concerned with building the case against her main suspect. Clarissa notes a parallel with a case from the start of her career.

A post-mortem on a victim of domestic violence brings back troubling memories for Nikki.

With Jenny's murder unresolved, her friends at the women's refuge seek answers.

When a skeleton is found buried in cement, the team have to work out how and why he was found there. Meanwhile, Clarissa receives some devastating new about her mother.

As the team looks further into Hope's death, they find ever more questions and realise more crimes were committed decades ago that need resolving. Clarissa has some difficult choices to make.

Thomas investigates the case of John Sealy, a soldier who died during a military training exercise involving exposure to CS gas. It appears John died from an aneurism, but when Thomas discovers the trace of a possible nerve agent in his system, the family are desperate for answers. Was a chemical weapon involved or is there a more innocent explanation?

It appears John died from an aneurism, but when Thomas discovers the trace of a possible nerve agent in his system, the family are desperate for answers. Was a chemical weapon involved or is there a more innocent explanation?

A prisoner is killed during a riot, Nikki is on hand to investigate the scene, inside The Prison she recognises a face from her past.

As the team investigate a second death, Nikki's theory starts to fall apart. Can she put her fixation with Scott aside and find the killer?

A swimming instructor is found murdered in her flat, evidence from the scene pointed two suspects, including the her ex, a former police officer.

The team struggle to identify the bodies buried in the garden at the house Laura visited before her death.

Nikki, Jack and Adam are brought in to investigate the murder of a surgeon in a hospital. DNA evidence suggests the impossible when it implicates a patient who was under anaesthetic at the time of the killing.

With their suspect in a coma and an attacker seemingly at large in the hospital, Nikki calls on Adam's expertise to help solve the case.

The murder of a promising boxer draws Nikki and Jack into the world of underground boxing. Meanwhile, Jack's brother Ryan is released from prison.

Jack, Nikki and Simone investigate another death connected to the underground boxing ring. Jack's loyalty is tested when he fears Ryan has put Cara in danger.

Nikki's students make an alarming discovery while dissecting a body donated for their training. Jack and Simone try to save care home residents from a flood

Stranded in the flooded care home, Jack and Simone fight to keep the residents alive - but Nikki discovers that they may be trapped inside with the killer.

Sam Ryan recruits the Lyell team to investigate the assassination of the health secretary, but Nikki is unsure whether Sam knows more than she's letting on.

DNA evidence linked to the health secretary's assassination forces Nikki to face her past in the present. As her investigation progresses, Nikki realises that its consequences will affect her, and her profession, forever.

When a woman confesses to murdering her husband, the Lyell team must determine if all is as it seems. Meanwhile, Simone is shocked to be reunited with a detective from her childhood and struggles to untangle her past.

A secret from his father propels Jack to Belfast. Meanwhile, Simone and Nikki investigate the mystery of a burned body. As familial secrets come to the surface, Jack faces tragedy head on.

The death of an investigative journalist throws the spotlight onto Sam Ryan. Nikki begins to realise that the implications of her discoveries will challenge the principles of forensic science.

Events lead Nikki to conclude that getting the truth will put the Lyell team and everything they love in danger.

The team are propelled into the criminal underworld of a notorious mafia group, the Ndrangheta when a man is thrown from a high-rise building.

Nikki becomes involved with the Ndrangheta mafia-group. An unlikely alliance leads her closer to the truth, hence follows some collateral damage.

The Lyell team investigate when a lorry is found in Kent with people locked inside. However, some have survived but will not speak to police. The team and the police delve into a world of drugs and human trafficking.

The team continue to try and find out information about the lorry of bodies with a dead driver at the wheel. Shocking leads shed some light on the case. An ethical dilemma grips Gabriel and there is a surprise visit.

The Lyell team are drawn into the dark side of social media when a man is found dead in a tent at a music festival. But with more twists coming and a heavily pregnant DI, can the case be solved?

The investigation continues to take unpredicted turns, with Nikki managing to get behind the mask of the lead suspect.

Business leaders and environmental activists clash in a small town. With a sabotaged train and a dead mayor, the activists become suspects.

The Lyell team return to the train tunnel and uncover some difficult truths. Meanwhile the police raid the protester camp, desperate for answers. Family ties are pushed to their limits.

Nikki and the team start to build a picture of what happened, but they doesn't get much out of it. Jack comes to the aid of an old friend and is sucked into a difficult case.

The local CID finds dissent within the ranks as the evidence mounts against the accused police officer.

The death of an investigative journalist throws the spotlight onto Sam Ryan. Nikki begins to realise that the implications of her discoveries will challenge the principles of forensic science.

Whilst fibres under the nails of the latest victim provide a link the the St Jude's homeless hostel Lana is interviewed as a formality and states that Owen Hanmore was outside the tube station at the time of the first death and must thus be innocent. Clarissa, however, finds evidence of Lana's prints on the victim's phone and Lana and Hanmore are both increasingly under suspicion as they locate Lana's child and attempt to kidnap him. The child will provide a link to the murders whilst Nikki helps Luke to come to terms with his own past.

Leo feels guilty when Helen kills herself,leaving an explanation on Camcorder that she took the tissues to further scientific research. Aware that Mears killed more women than he was imprisoned for, Leo tells the police about the arrangement with Annie,scaring Andy, who believes that Mears will have his mother murdered for the breach of trust. It is also revealed that Annie believes her daughter was one of Mears' victims,hence her involvement with him. When Annie disappears Nikki visits Mears,who agrees to tell her about all his other victims. He appears to have won his mind game with her but his possessiveness over his copy of 'Paradise Lost' and Nikki's chance remark about an elderly lady she met who knew Mears yield results.

Nikki Alexander finds herself working on a case from her past. Four years previously, she had been instrumental in getting 17 year-old Anna Holland acquitted of a murder charge. She had been accused of egging on her boyfriend in the murder of a young mother they chose randomly. Now, while under police protection, her body has been found in a burnt car. The autopsy reveals that she had been stabbed but had died from carbon monoxide poisoning and so was burnt alive. Nikki also receives a surprise visit from her estranged father who wants her to perform a second autopsy on a friend who recently died.

Nikki and Jack are called to a tube station where a homeless ex-soldier has fallen under the wheels of a subway train. Leaving the station hotel receptionist Lana Sutherland meets another homeless man, Owen Hanmore, whom she invites to stay with her, becoming his lover. Meanwhile a series of murders occurs with no visible link, beyond the fact that all the victims had used the same tube station.

Little Lizzie Craddock goes missing after social worker Louise Dillon has unsuccessfully applied for a care order given her father Johnny's violence. At the same time suspected paedophile Dale Barge is murdered and pictures of Lizzie are found at his flat. Young Kevin Garvey leaves care but goes to stay with his grandparents, rather than inadequate mother Niamh and stepfather Daniel, whom he blames for himself and his sisters going into care. Then Daniel is found dead.

Leo gives evidence at a custody hearing in the wake of a child's death,his opinion over-ruling that of Dr Helen Karamides,which annoys her former pupil Nikki,who sees Helen as the victim of the male establishment and cannot believe the accusation that Helen is retaining tissue samples from past cases. Nikki is also approached by Andy Farmer. His mother Annie was the appropriate adult at the interview with serial killer Arnold Mears,who now directs Annie to the sites of his victims' remains where she collects their bones. Andy wants Nikki to help identify them. Nikki also discovers that Helen had a professional involvement with Mears.

As the team investigate a second death, Nikki's theory starts to fall apart. Can she put her fixation with Scott aside and find the killer?

A prisoner is killed during a riot, Nikki is on hand to investigate the scene, inside The Prison she recognises a face from her past.

Nikki is arrested when a former colleague she came to blows with is murdered. Tony fears that his son David may be involved in the killings, but Nikki has her suspicions about someone once close to her.