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.

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.

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.

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.

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

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.

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?

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.

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.

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.