New boss Robert Strickland asks the team to reopen the case of David Barrie, a barrister found dead, bound and gagged, in his car in the 1980s. The case was a rare instance of officer-in-charge Ronnie Ross's not getting his man. Chief suspect Michael, now a transsexual called Michaela, had an alibi, but Michaela is involved with Elaine Wanless, a former brothel-keeper who reveals the dead man's penchant for bondage. The team is convinced that both know more about the death than they claim.

UCOS reopens the case of a woman who has been left comatose for eight years.

In 1992, 18-year-old Hannah Taylor was kidnapped, and now a body, once believed to be hers, is proven to be another girl's. Hannah's mother, Madeline, an ex-alcoholic G.P., is prickly but admits to paying a twenty-thousand-pound ransom delivered by an-ex cop who was, in fact, her married lover. Jack suspects that this was a scam to part Madeline's former husband from twenty thousand pounds. The mystery intensifies when Jack traces Hannah, now married, who states that she left her mother a note to say she was going to a pop festival where she met her husband. It intensifies even further on the discovery that Madeline already knew Hannah's husband.

The team is supposed to be investigating the conviction of Stanley Ackerman, whose wife is continually protesting in front of the station. The man was convicted of setting his factory on fire, but Jack sees a number of anomalies in the evidence. But having lost £10,000 in a poker game, Gerry is given the possibility of wiping out the debt when the winner asks him to investigate his father's murder 20 years earlier. The man, Joe Jacobs, had been attacked on the street, but it was put down to a mugging, with no arrests made. Gerry tries to investigate the case on his own, but his colleagues, including Supt. Sandra Pullman, are soon on to him. Jacobs was in debt to bookie George Morton, but they determine that his death was related to the kidnapping of a champion greyhound racing dog.

The team investigates the murder of an unidentified young woman who was found in the woods some 18 years previously. The original pathologist on the case, Professor Mears, has kept all of the evidence in the case and has longed for it to be reopened. He has even given the girl a name, "Millicent". Working with what little information they have (the young woman had red hair and had syphilis), they first seek to identify the girl. She also had been cut up by an expert carver. Throughout this time, Gerry Standing is going a bit mad, as he has given up gambling, but every horse he would have bet on has won.

With the recent release of Cabinet papers under the 30-year rule, Jack pushes to reopen the investigation into the death of Joe Walsh, a left-wing union leader. His body was fished out of the Thames in the mid 1970s and his death put down to suicide, but it was clear that the Cabinet wanted his antics stopped, and Jack wonders if someone might have taken those wishes a little too seriously. There were rumors that Walsh had fiddled the union books, and several of his contemporaries are convinced he was disposed of by MI5. Meanwhile, Brian decides to stop taking his medication, with expected results.

The vicious criminal Chopper Hadley, who has been back in the country for a week, is searched for by the team. However, Halford is viciously intimidated and the squad start to realise the full danger of their target. Desperate measures are used and Brian is sent undercover to get Hadley once and for all.

A young woman insists that the suspicious death of a local librarian was because of witchcraft, and the team are drawn into the world of magic and the supernatural. A series of strange events occur, and they are put under increasing pressure. The squad become convinced that the supernatural exists and struggle to remain cynical.

When one of Gerry's informants returns to England and provides him with new evidence, the team re-open the case of a 1987 bank robbery where one of the bank employees was killed. The prime suspect was always Ray Cook, but the police could never get the evidence to charge him. Cook's alibi has always been that he was with his dying mother at the time of the robbery but the team find evidence that brings their basic premise into question. They also determine that the bank robbers may have had inside help, including that of certain police officers.

The team are on the case of the ice cream bandit, an armed robber whose targets were the ice cream vans of two feuding ice cream manufacturers in the mid 1990s. The battle between the two families erupts into violence, so UCOS decide to track down the bandit and stop the conflict once and for all.

Luke Hanson has recently been released from jail after serving 8 years for setting a fire at his local school in which the caretaker had been severely injured. He was across the country committing another crime at the time and would like the team to reopen the case. This was Jack's last case before retiring to care for his wife, who was the victim of a hit and run driver. Supt. Pullman gets an offer of promotion that she is finding very hard to resist, but it would mean leaving the squad. A woman who claims to be his daughter approaches Gerry, and Brian rekindles an interest in war gaming. In the course of investigating the school fire, Jack learns the identity of the hit-and-run driver and decides to take action.

Jack's finally discovered the identity of the hit-and-run driver who murdered his wife and he is now prepared to risk everything to kill the man responsible: crook Ricky Hanson. Determined that Hanson should meet the same fate as his wife, Jack lies in wait in a pub car park, engine running. Sandra becomes aware of the situation. She acts fast to prevent him confronting his nemesis, but it results in a crash that jeopardises the future of the entire team. With Jack, Gerry and Brian hospitalised, Sandra's forced to accept temporary help at UCOS from the super-efficient DCI Karen Hardwick, a woman who irritates Pullman on every level. As she struggles to keep the truth behind the crash a secret from Strickland, Sandra becomes deeply suspicious that Hardwick's been recruited to spy on her. And with Jack clearly on the edge and suffering temporary memory loss since the crash, Sandra has her work cut out in trying to keep Hardwick in the dark. Threatened by a new face in the office and desperate to prove that they're still a crack team, even from a hospital bed, the boys need a case. When their consultant, Dr Finlay McKenzie, mentions the suspicious death of a patient, Alan White, on their ward 10 years ago, they seize the opportunity to re-investigate, hoping it will hold the team together. But is Jack still in mortal danger from his nemesis?

Sandra's private and professional worlds become intertwined when her mother has a fall that means she needs to go into a care home and her first choice is revealed to be the scene of a suspicious death a year earlier. Jack, Gerry Standing and Brian decide to go undercover at the home.

When an armoured security van is discovered at the bottom of a lake, the team makes a link with the murder of a woman 17 years previously. The husband of the deceased, who owned the company which the van belonged to, seems to be the prime suspect but when he is provided with an alibi, Sandra decides to dive down to examine the vehicle herself and uncovers the murder weapon. However, the killer is about to strike again.

The team investigate when the family of Richard Dunne, one of the last men to be hanged in Britain, say he was the victim of a miscarriage of justice due to police corruption.

When Brian's dog finds a body on a common, it prompts two people to confess to murder. But when the body turns out to be over 600 years old, Sandra, Jack, Brian and Gerry must discover why the pair took responsibility for a crime they couldn't possibly have committed and if they are in fact the perpetrators of other killings. Elsewhere, Strickland is rather more keen for them to solve an even more tricky mystery closer to home.

Pullman's mother has a stroke, and this event leads Sandra to start asking questions about her father, but she ends up losing her trust in the team when she discovers they have withheld information about her father from her. The revelation that he committed suicide while under investigation for corruption causes the detective to doubt all she took for granted, but she tries to set her feelings aside when she is asked to look into the death of a circus ringmaster who burned to death in his caravan, leaving only his feet behind.

The trial of Ricky Hanson starts, and the members of UCOS are scheduled to appear as witnesses. Hanson is the man who killed Jack Halford's wife, but he's on trial for attempting to murder Jack, who was recovering from a car accident over a year ago. Hanson's barrister is clearly out to discredit each of them individually. While at the courthouse, they are asked by an acquaintance of Jack's, Sam Tallis, to look into the death of Ralph Wheeler, who was killed and left his fortune to a tart named Carrie Soper. As they look into the case, they find several possible suspects, including a solicitor, a doctor, and someone with a lengthy criminal record. In the end, the case revolves around a car accident and organ donation.

With Jack Halford away following the acquittal of Ricky Hanson, Sandra, Gerry and Brian investigate the death of actor Michael Austin, who was shot dead during the performance of a play. The gun was loaded with blanks, but a piece of metal lodged in the barrel killed him. The death was ruled accidental at the time, but Austin's daughter Catherine has recently written a book, and new evidence in the form of a threatening note has come to light. The team is joined by a young officer on the fast track for promotion, James Strickland, the DAC's nephew. They interview Austin's then wife, Helen Brownlow (she's also an actress and the one who fired the gun on stage) and the stage manager, Derek Bennett, as well as Catherine Austin's agent, Mel Simons, who sent the note to her publishers. Forensics indicate that the letter may have been doctored. Meanwhile, the boys have forgotten Sandra's birthday, but she does accept a dinner invitation from the young Strickland.

The UCOS team investigates the death 10 years ago of popular disc jockey Johnny Deacon who died in a fire when the radio station was set alight. The police knew it was arson, but were never able to find enough evidence to charge anyone. Johnny was very opinionated on air and seemed to go out of his way to be offensive at time. He also had a number of female admirers, one of whom may have been stalking him. With Jack having virtually disappeared meanwhile, Sandra finds herself under pressure from DAC Strickland to start interviewing for his replacement. Despite their best efforts, Jack is nowhere to be found.

Brian finally locates Jack who returns to the UCOS team but remains silent about his lengthy absence. The team investigates the death of rock star Andy Fletcher, who supposedly committed suicide in 1975. Gerry speaks to a dying woman who suggests otherwise. She overheard a fight just before his death, and although she reported it to the police after Fletcher was found dead, her information is nowhere to be found in the files. The band's former manager Clive Evans found Andy but doesn't believe there was foul play. The three remaining band members all deny any special knowledge of what happened, but one of them kept Andy's royalties.

After a bent detective is discovered on the force, the UCOS team is tasked with investigating his only unsolved case. In 1998, assistant brewer Graham Thompson was found drowned in a vat of beer at Felspar Breweries. The dead man's girlfriend has always maintained that it wasn't an accident. Everyone concerned, including Sir Freddie Felspar ,says he was a brilliant brewer and a great loss. The original investigator failed to interview either of Sir Freddie's children and son Julian is now the company's Chief Executive. The brewery had won the gold medal for its beer 5 years running but in 1998 they lost to a small brewery that made its reputation on the win. The team now wonder if industrial sabotage may be at the root of the mystery. Meanwhile, Sandra continues to investigate her late father's activities while he was on the job.

The UCOS team investigates the death of Eric Trimble, a soldier who was beaten to death in 1991. Their informant tells them that he and Eric, while still in the Army, were part of secret medical experiments that left the survivors paranoid. Their attempts to investigate those experiments come up against a military establishment that puts every possible in their way, including a visit from MI-5. As the investigation continues however, they discover several other possible motives including the fact that Eric was a bully and also gay. The fact that he is black also makes race a possible motive. Meanwhile, Brian continues to struggle with his alcoholism.

Having lapsed into alcoholism, Brian is booked into a rehabilitation clinic run by an order of monks. A chance remark by Father Bernard leads Brian to telephone Sandra late at night to tell her that there was an unexplained death in the clinic nine years previously. To prevent Brian obsessively investigating by himself, the team take up the enquiry into the death of a heroin addict, and infiltrate Gerry into the clinic as a compulsive sex addict. Brian's wife Esther discovers the whole team at the clinic, and is furious, but Sandra persuades her that it is the only way to ease the strain on Brian. By the time Gerry's cover has been blown, the team have discovered that the dead man, Robert Smith, probably took to drugs as a result of post-traumatic stress disorder, after witnessing or even participating in events in the civil wars which followed the break-up of Yugoslavia. They also discover that some of the staff and even the monks at the rehabilitation centre have secrets they wish to conceal or have concealed their origins.

Ex-actress Gloria Gransford draws the team's attention to a clip, posted on the Internet, from a film she made in 1990 called 'Shadow Show', after which the producer Max Stone was stabbed to death and leading lady Eva Roderick disappeared. Director Don Maddox, Gloria's ex-husband, is egotistical and evasive, and the only other surviving crew member from the film - who posted the clip - is found dead. His young boyfriend goes on the run and located Eva, who now has a new identity. A siege situation develops, which Brian defuses.

Five years earlier Dean Scott was found dead of shot-gun wounds and suicide was the verdict. Now ex-hooker Alice Hill tells the team she was at Dean's house at the time and believes he was murdered. Mike Barnes, Dean's shifty partner, rooked his widow Pam and turns out to be an ex-bank robber, who used the loot to start the business. The search switches to the other robbers, one of whom has gone straight and the other - who fought with Dean the night before the death because he was seeing Pam - is under witness protection. The missing loot is found but the fact that Pam and Alice already knew each other complicates the murder theory.

The team meets a girl called Jo, who is heckling Right Wing comedian Ray Harris. Her aunt Sarah Jones and Sarah's partner Daniel disappeared twenty-five years earlier whilst engaged in a campaign against Ray's sexist and racist routines. The pair actually infiltrated an extreme group of Nazi supporters called the Twenty-Fours, which numbered Ray, policeman Frank Paterson and Ricky Hanson who killed Jack's wife. Frank was also undercover,trying, unsuccessfully, to bust Hanson's drug racket but now joins with Sandra to nail Hanson once and for all, with unexpected help from Hanson's son Luke, who has made a shocking discovery about his father. Ricky Hanson is charged with murdering the couple - and, at long last, there is closure for Jack too.

Whilst Strickland's friend Alistair Dudley is entertaining them on his cruiser at a marina, the team see Leanne Sweeting harangue another boat owner Lawrence Fisher. In 2001 a collision between a tug captained by Leanne's father Neville and a cruiser owned by casino boss Grant Milburn collided, killing five people including Milburn. Neville was blamed but Leanne believes Fisher sabotaged Milburn's boat, as they were business rivals. Certainly Fisher profited by the tragedy in business terms. Milburn was going to open another casino and his croupiers were also prostitutes, but the case is altered by the knowledge that Milburn's wife's lover was also on his boat and engaged in a brawl at the crucial moment.

Thirty-three years after the corpse of Dr. Simon Lockhart was found in his butcher's shop at Smithfield the body of Harry Eldridge is discovered - cut into pieces. The doctor used to gamble with Harry and other butchers - now all retired - and Jack discovers from the Lestade brothers, butchers who are Gerry's cousins, that Gerry and other butchers were in the financial clutches of gangster Danny Paye, now in a care home. Brian learns that the doctor performed illegal abortions - anathema to strict Catholic Eldridge - but Sandra gets the biggest shock on finding that she has an illegitimate half-brother, who was adopted by Eldridge's widow, Julia. Unfortunately his DNA is all over Harry's corpse.

Sandra does not believe recently released paedophile John Davies when he owns to killing 5-year old Yasser Gorton-Blackledge, who disappeared after going on a Free Palestine march with his left wing parents Anne and Fred in 1985. Now divorced, Anne still campaigns for liberal issues but Fred is a hard right reactionary and misogynist. Davies eventually admits to Sandra that he was bullied into confession by Anthony Vernon, a violent disciple of Fred who once hoped to make his name in journalism from Yasser's case. Another ex-activist, kindly nurse Gillian Withall, adopted a little boy at much the same time that Yasser disappeared and, as Gerry and Brian read through the files MI5 compiled on the Gorton-Blackledges it becomes more than likely to them that Yasser is still alive.

The team is asked by Dawn Abbott to reopen a fourteen year old case of a fire at the Union drinking club, which killed gangster Mark Johnson and three staff members. It was thought to be an accident but Mark told Dawn days before the fire that he thought somebody was out to kill him. Mark's brother Danny resents any suggestion that he was involved but fire investigator George Mackie tells the team that he thought at the time that the blaze was suspicious and the widow of the painter whose materials were supposedly to blame for the fire recalls that he was handsomely paid soon afterwards. Ultimately the culprit proves not to be a person with a grudge but a serial arsonist hoping to get away with as many fires as possible.

In 1999 promising young boxer Eddie Mayfair was shot dead but his rival in the ring and chief suspect Milton Joseph had an alibi and other likely suspects have all since died or disappeared. Now the murder weapon has been found at last. Eddie's widowed mother has moved in with his former agent Harry Gallo and his old sweetheart married his sparring partner Danny. Jack discovers that Eddie was in a rival street-gang to Milton, long before they met in the ring and Milton's gang members were the men who have now all disappeared. The biggest breakthrough, however, occurs with the knowledge that Eddie was meant to throw the fight with Milton as certain people had money on that result - the same people who killed Eddie to stop him talking.

Detective inspector Frank Paterson joins the team to reopen a thirty year old bullion robbery after he has tracked down the getaway car. Two guards died, allegedly at the hands of vicious Michael Denby - the fourth man in the robbery, who, unlike the other three, was never accounted for and is still at large. Frank and Sandra do not get on and she is sceptical when he claims that John Felsham, now a deputy assistant commissioner, was a bent copper who tipped Denby off, Felsham telling her that Frank has long held a personal grudge against him. However Felsham arrives unexpectedly at a back street pub once used by Denby where Frank and Gerry are following a lead and Frank fights him. As a result Felsham wants UCOS disbanded. But the team are determined to carry on and, backed by Strickland, they make sure that they get their man.

The UCOS team reinvestigates a highly sensitive case when new information links an unexplained death to a series of drug rapes in East London.

In 2004 physics professor Philip MacKenna was apparently abducted from a Paris-bound train. His journey was last minute, after a colleague was robbed, and witnesses at the time proved to be using false identities, suggesting a plot to kidnap him for his expertise. Now his wife is getting cryptic emails, impossible to trace, suggesting he is alive, but she has been holding back a secret. A tip off from a Whitehall mandarin leads the team closer to the truth.

Stephanie Parr tells the team that her biker boyfriend Reese Chapman, as a rite of passage, must kill a rival gang leader who supposedly murdered his father Eddie, founder of the violent criminal Braves biker gang when she is sure the killer was Marcus York, the club's current president. Superintendent Barlow asks the team to back off as he is surveying the Brave for drug-peddling but when Stephanie is attacked Sandra resolves to continue, despite a lack of witnesses for fear of York and Barlow's unhelpful attitude. David, Stephanie's father, holds the key but the identity of the killer does Barlow no good.

A website highlighting unexplained disappearances alerts the team to the death of young mechanic Christopher Collins seven years earlier. Sandra discovers he was really called Tommy Barton, and was on a witness protection scheme having testified against drugs baron Derek Robinson. He was, though, a drug smuggler himself and was having an affair with his boss's wife. In tracing the killer the team is much aided by the hypnotherapist treating Brian's insomnia and they also learn that UCOS will not be terminated to save money.

When keeper Zac Halsey's corpse was found in the tiger enclosure at Harefield Zoo in 2006, the assumption was that he had been mauled to death, but blood found during the refurbishment of his flat now suggests that he was murdered and his body dumped in the compound. He had recently been to Spain where the knife that killed him was purchased. An animal rights campaigner, sacked security guard and a couple with whom Zac enjoyed extreme sports, are all suspects and all seemed to have been in the zoo the night Zac died. Jack works out the killer's identity even though it means he and the team miss his presentation for bravery as a result.

The team is less than pleased when arrogant civil servant Stephen Fisher coerces them into investigating the murder - in 1851 - of Abigail Padua, a mathematical expert whose death led to the collapse of her family business and a widespread financial crisis. With no living witnesses and a different geography to the time the team must pore over the original statements to prove that the killer was a witness who lied to the police. However, they, with Strickland's backing, have another mystery on their hands - Fisher's obsession with cracking the case, which itself could have far-reaching effects in the modern business world. Jack however is able to thwart Fisher before he leaves the unit for good to spend his last days in France.

At Christmas 2008, Foreign Office employee Annabel Tilson's body was found in a frozen lake, the assumption being that she killed herself after suffering a miscarriage and demotion at work when her lap-top, containing sensitive information, was stolen. Now her twin Minnie has unearthed a video showing that Annabel met somebody prior to her death and was probably murdered. Sandra learns that Annabel was deliberately made a scapegoat to get her out of the way on discovering her married boss's affair with a colleague. She also stumbled on insider information trading, but the key to her death turns out to be her personal, rather than professional life.

In 2003, 17 year old Georgia Wright vanished after a university disco in Scotland. Now traces of her blood are found following a garage raid in London, bringing dogged retired police inspector Steve McAndrew to UCOS to ask them to investigate. CCTV proves that Georgia was not one of the robbers but worked at the garage as a cleaner,,disappearing soon afterwards. They then get a lead in that Shane Morrison,,one of the last people to see Georgia alive, is a fantasist, who persuaded another girl Sophie that he was a secret agent, forcing her to live life on the run with him. The team believes that Morrison is still about and has Georgia in his power. Though the others initially find Steve irritating and his accent incomprehensible, Gerry warms to him over a few whiskeys and, the case over, Sandra has a proposition for him.

Some months after his mysterious disappearance the corpse of young police computer operator Martin Longthorn is smuggled into the morgue at a London teaching hospital. Though he died of an aneurysm the UCOS team are involved as his date Catherine, the last person to see him alive, claims he disappeared suddenly after taking a very important phone call. Investigation of Martin's computer shows he was apparently a member of the Roguenet Group, an organization that hacks into corporate companies and banks to sabotage them. However it turns out that he was actually infiltrating them to unmask their leader Boz, making his death seem more suspicious. Brian, meanwhile, is jealous of Gerry's rapport with Steve, leading to Esther making an effort to rectify the situation.

The team reopen the murder of East German refugee Max Klein, whose last words were 'Blue Flower'. Visiting the site of his death Sandra and Steve meet Grace Cusack, whose son was killed at the same spot a year before Max's death and tells them he came to England to look for his daughter Mia who had escaped East Berlin ahead of him. Meanwhile Gerry and Brian visit a recycling centre where Max worked and learn that he stole bundles of documents but are challenged by arrogant Inspector Rosser, who claims that they could interfere with his investigation of the centre in connection with identity fraud. When Mia is located she denounces her father as a member of the Blue Flower group which was pro-Stasi though ultimately the deaths of Grace's son and Max prove to be related and less political than expected.

Following an attempt to kill Stephen Fisher, Strickland summons the team to a secret meeting. He tells them that thirty years earlier he and Fisher were part of an intelligence group investigating the IRA but their source journalist Simon Bisley was killed in a hit-and-run and the investigation ended. Now others of the group are being murdered. Bisley had linked the IRA to a career criminal Carl Dillon who, according to Gerry's informant Tinker, has just recruited two assassins and a telling document which could incriminate Dillon was stolen from Bisley's office. However Brian believes that a rogue member of the former secret service team has a vested interest in stealing the document and silencing their colleagues over it, giving Strickland the means to go after them though the team is dissatisfied with the result.

Gerry and Steve go to Glasgow, ostensibly to advise on establishing a UCOS office there but are asked to investigate the nineteen year old death of bookmaker James Soutar, given that the investigating officer at the time Frank McNair was suspected of corruption. He was also the man who ran off with Steve's wife. The pair are surprised to learn that Soutar left fifteen thousand pounds to Cathy Sinclair, who claims she never met him, as well as legacies to children's charities. However Charley, Steve's younger girlfriend, tells Gerry that she and Cathy were in care together and that Soutar was involved in a vice ring, grooming girls in care for sex. The duo solve the case and, before returning to London, Gerry helps Steve get his revenge on McNair.

Whilst Brian faces disciplinary action for a death in custody from his past the rest of the team discover the gun that killed drug-trafficker Christian Highsmith in 1998. The same gun killed a young boy, Danny Bossano, in 1982 in Gibraltar, a port of call for the ships on which Christian allegedly hid the drugs. The UCOS team go to Gibraltar to meet Superintendent Cruz, the local cold case chief, who believes Danny was part of the dope-smuggling gang. The fact that the gun was army issue also leads to the evasive commander Adam Sinclair whilst Sandra quizzes casino owner Harry Truman, who had been a friend of Christian. Gerry and Steve visit Truman's casino but accidentally get locked in a shipping container whilst shipping agent Gordon Fletcher, an associate of Truman, is found dead.

To the annoyance of Gerry, who arrested him for killing his wife sixteen years earlier, Scott Bunce is released from prison when evidence is found to suggest an unsafe conviction. His daughter Lizzie, who saw him standing over the corpse, and the neighbour who saw him leaving the house afterwards are both convinced of his guilt and Lizzie is terrified of seeing him. Then Bunce disappears after a gangster associate of his is severely beaten up. Brian visits his estranged son Mark, who tells him he is about to become a grandfather. They make their peace as Mark helps Brian find proof of Bunce's innocence, leading to the exposure of the real killer. However Brian, after being declared a hero, is told by Strickland he must leave UCOS for giving Sarah Kaye the tape he illegally made of Embleton's confession.

Now dismissed from UCOS Brian is persuaded by Esther to help her friend Margaret Kirby find her brother Peter Sale, who disappeared six years earlier. In the mean time Brian is bothered by journalist Maxine Wilson, whom he believes has been sent by Embleton to discredit him, and needs Strickland's help to get rid of her. Brian visits Jonathan Epstein, jailed for killing his wife Florence for her money, along with his girlfriend Annabel, who seemingly disappeared with the cash. Sale was Epstein's accountant but Epstein does not know his whereabouts and after the visit Brian is attacked. Accompanied by Esther, Brian sets out to find clues to locate Sale, in the process crossing paths with UCOS, who are investigating a con artist with links to Epstein. Eventually Sale is found and, before parting company with UCOS, Brian discovers that somebody is an impostor and Esther has to save him from being killed by them.

UCOS reopen the thirty year old murder of porn king Jim Hockney when his daughter Sara reveals that a DNA test proves she is not his daughter. Her mother Jane cannot provide any answers as she and Jim both had several sex partners. Jim's girlfriend at the time, singer Angela Gold, was charged but acquitted of the murder and now seems to have disappeared. Brian's replacement Dan Griffin arrives, albeit late and is initially treated with hostility by Gerry, who thinks he is a spy. Nonetheless Dan tracks down Angela though in the meantime Sandra learns that Jim's brother Colin sold Jim's porn empire very shortly after his death to his main rival Gavin Reason. Furthermore Jane and Gavin were lovers, Gavin proving to be Sara's father though he was unaware at the time. However it is Gerry's collection of some of Jim's old films, supposedly confiscated by Vice Squad, that identifies the murder weapon and leads to the culprit. The case closed the team watch Angela perform at Ronnie Scott's Jazz Club.

Following the 1997 General Election Ben Ransley, a young researcher for successful MP Liz Jackson, was murdered and the case is reopened on the discovery of £40,000 in an off-shore account in his name. Ben's best friend, arrogant lobbyist Eddie Trenton, gives Sandra a photo of Ben with his girlfriend, who turns out to be Hana, the Bosnian wife of tycoon Peter Russell, and she also disappeared in 1997. French policeman and former war crimes prosecutor Max Clement comes to London and tracks down Hana, whose whole family was killed in the Bosnian war. Hana believes Ben, with whom she was set to elope, was killed by the man who got her to England and introduced her to Peter but Dan discovers that Ben was in a position to leak information about a government arms deal, which would have been injurious to certain people. This solves the case.

Seventeen years earlier Sandra's first case involved the disappearance, never resolved, of music student Lesley Hewitt and now Lesley's sister Emma has been sent a photo of Lesley walking in a park just before she vanished. Sandra believes that a jogger in the picture was a serial killer responsible for the deaths of other young girls, possibly working with a female accomplice as Emma says that Lesley was offered a gig before she vanished. Ex-model Annie Banks and bookshop owner Stuart McKelvie are also in the photo, taken by Greg Banks, a recently deceased photographer whose studio contains several pictures of women who were abducted and killed. Annie and Stuart initially claim not to know each other but Sandra breaks down their stories and discovers that Annie knows who the jogger is. After concluding the case Sandra leaves UCOS to work with Max Clement.

Fresh from her successful SWAT raid on a group of Russian gangsters DCI Sasha Miller arrives at UCOS to replace Sandra. She is friendly and informal but initially fails to win over Gerry, who misses Sandra. Her first case involves the twenty-five year old murder of Italian Allesandro Manzini, reopened when a knife is found at the allotment he once tended. Massimo, whose son married Allesandro's daughter Giulietta, tells the team that there was anti- Italian feeling on the allotment, especially from two World War Two veterans, whilst lorry driver and druid Ray Barlow is also suspect, having disappeared after the murder. This suspicion is heightened when Giulietta and Ray admit to an affair but Dan's research into wartime Italy changes everything, leading to a confession. Sasha's private life, however, does not run so successfully.

The discrediting of DI Hennessy as corrupt throws into a new light some of his more high profile arrests, including that of crooked businessman Edward Monroe, jailed for killing oncologist Dr Caldwell, whom he blames for the death of his daughter. For Sasha, now alone after discovering her husband's infidelity, the case is painful as she has always believed Monroe murdered her former colleague DC Tyler. As fresh interviews are conducted, it turns out that Caldwell was not a pleasant man and had made enemies of his colleague, Dr Hallerman, passed over for honours; Daniella Yates, director of a cancer charity who was having an affair with Caldwell; and Caldwell's duped wife. However a statement from Grace, a hotel employee of Monroe, throws a more humane light upon the convicted killer, as well as giving Sasha some closure for Tyler's death. Steve, meanwhile finds himself billeting his son Stewie, who has run away from home.

Thirty years after the death of a suspected terrorist, the man's daughter receives an anonymous note claiming he was murdered. Clues lead the team to the Greenham Common antinuclear protests of the 1980s.

When film critic Oliver Houghton's corpse is found in a sewer Sasha is reluctantly forced to work with Ned as Oliver had been a witness in the unsolved case of gay artist David Straka two decades earlier. Both men were drowned and Danny sees the river Fleet as a link since it featured in David's last project. David's friend Ruth Shireen tells the team that David and Oliver got involved with the occult due to the unpleasant Cyril Watkins though Cyril, now Cecily after gender realignment, explains that there was no harm intended. However a woman playing the part of a sacrificial victim in David's film about the mysteries of the Fleet accidentally died. A trip to the sewers locates her corpse and Sasha beats Ned to finding out her identity and solving both cases.

The team notice that DNA from teen-aged market trader Spencer Rogers, arrested for throwing a brick on the motorway, matches that of interpreter and chess club member Agnes Bradley, murdered in 2010 and when Spencer's mother Kelli tells Sasha that Spencer was the result of her being raped by an unknown man it is apparent the rapist is the murderer. Suspects include Jeremy Powell, who, according to chess club captain Viktor Proust, smarted because he could never beat Agnes and Chilean diplomat Carlos Alvarez who had Agnes black-listed after one of her translations warned students against his womanizing. Whilst the rest of the team is busy trying to catch the murderer Steve is occupied with bringing his hate-filled dying father Robbie to a hospice in London.

After an amateur sleuth is murdered, a photo of Danny is found at the scene. It turns out Danny was her friend, and he vows to find the killer. Clues lead to a 25-year-old murder and a trip to the countryside.

Over thirty years after school-girl Amy Taskerland died at an end of term disco a time capsule is unearthed, containing a tape where she expresses fear of Alec. Neither her father William or best friend Harriet can identify Alec though Amy's headmaster falls under suspicion as he was having an affair with Amy whilst dating teacher Carla O'Brien. Then Danny discovers that Amy appears to have been reciting a speech to be used by the queen in event of nuclear war which leads to the identity of Alec and in turn to who killed Amy. Gerry meanwhile has a surprise on his future son-in-law's stag night whilst Strickland springs an even bigger surprise and Danny successfully plays Cupid for Sasha.

Gerry is personally involved when the body of Martin Ackroyd, his first inspector when he joined CID, is discovered having been missing for thirty years. Prime suspects are former officers Bryant and McCabe, whom Ackroyd believed to be corrupt and are now involved with career criminal Dominic Chapman, as is Ackroyd's ex-superior Ronald Sainsbury who colludes with them to discredit Gerry. Gerry tracks down Tommy Naylor, another crook the dead man had in his sights and whom Bryant and McCabe unsuccessfully attempted to frame. Gerry decides to take the law into his own hands after his daughter Caitlin is threatened but this only makes him seem guilty of the murder in Sasha's eyes.

With evidence suggesting that his cosh was the murder weapon and a trumped-up assault claim from Sainsbury things look bleak for Gerry but DAC Strickland is sure of his innocence and lets him go. With dangerous men in pursuit Gerry goes on the run with Danny, to whom he relates that Ackroyd was as corrupt as any of the other suspects and was in Chapman's pay. They call on Tommy Naylor, who directs them towards honest Ted Case, another retired officer and he gives them evidence of Ackroyd's involvement with Chapman. This in turn leads Gerry back to Bryant and McCabe and arrests are made, followed by recrimination, chicanery, a funeral and a departure.

Ted Case joins the team to reopen the murder of vicar Leonard Whitechurch, a white man with a black wife who was stabbed in 2006 after receiving racist hate mail. His widow Alicia tells them that his curate Wendy had a crush on him but she hung herself two years after his death. The poison pen letters are traced to ex-convict and white supremacist Kevin Duncan but Ted believes the motive to be more complicated than purely racial. Duncan admits he wrote the letters in revenge as the victim disapproved of his dating his daughter Sally but a revelation from Leonard's younger son Luke exposes a rift in the family and leads to the solution of the murder.

When the recently deceased pathologist Dr Hatton's findings are discredited the team looks into the 2005 drowning in his bath of cricketer AJ Da Silva, a suicide according to Hatton though AJ's father and brother are convinced he was murdered. Ted learns from coach Keith Ainsworth and former captain Ryan Reed that AJ was thoroughly disliked by the other cricketers in his side as an arrogant, drunken womaniser. In fact his affair with a team mate's wife was held responsible for the man's suicide. After another person is found dead the key to AJ's demise is found to be match-fixing and its consequences and, the case solved, Ted springs a surprise on his colleagues.

A blood-stained bust uncovered in a graveyard links to the 2008 murder of alternative health practitioner Jason Henway. Angela Morris blamed him for taking her late mother Gwen off chemotherapy but had an alibi. Jason's business partner Evan Langley stood to gain but points the team towards Jason's brother Douglas, a doctor practising cryopreservation, keeping the clinically dead alive through low temperatures, since he left the business having quarrelled with his brother on his wife's death. As well as solving the murder the team must also deal with Sasha's departure when she is offered an appetizing promotion.

On New Year's Eve 1999 progressive mental health campaigner Greg Collins was murdered and now the discovery of his diary is found, chronicling his fear of his likely fate. The team interviews his colleagues including Toni Pembury, who tells them that Greg was battling a drugs company, and Samia Khan, now a peeress, who fell out with Greg after leaving his mental health charity to set up one of her own. Then they are ordered to halt the inquiry, supposedly in the wake of the mishandled Henway case. When Greg's journal goes missing they must work unofficially to solve his murder - and work fast since UCOS is threatened with being disbanded.

Following an attempt to kill Stephen Fisher, Strickland summons the team to a secret meeting. He tells them that thirty years earlier he and Fisher were part of an intelligence group investigating the IRA but their source journalist Simon Bisley was killed in a hit-and-run and the investigation ended. Now others of the group are being murdered. Bisley had linked the IRA to a career criminal Carl Dillon who, according to Gerry's informant Tinker, has just recruited two assassins and a telling document which could incriminate Dillon was stolen from Bisley's office. However Brian believes that a rogue member of the former secret service team has a vested interest in stealing the document and silencing their colleagues over it, giving Strickland the means to go after them though the team is dissatisfied with the result.

Whilst Strickland's friend Alistair Dudley is entertaining them on his cruiser at a marina, the team see Leanne Sweeting harangue another boat owner Lawrence Fisher. In 2001 a collision between a tug captained by Leanne's father Neville and a cruiser owned by casino boss Grant Milburn collided, killing five people including Milburn. Neville was blamed but Leanne believes Fisher sabotaged Milburn's boat, as they were business rivals. Certainly Fisher profited by the tragedy in business terms. Milburn was going to open another casino and his croupiers were also prostitutes, but the case is altered by the knowledge that Milburn's wife's lover was also on his boat and engaged in a brawl at the crucial moment.

With evidence suggesting that his cosh was the murder weapon and a trumped-up assault claim from Sainsbury things look bleak for Gerry but DAC Strickland is sure of his innocence and lets him go. With dangerous men in pursuit Gerry goes on the run with Danny, to whom he relates that Ackroyd was as corrupt as any of the other suspects and was in Chapman's pay. They call on Tommy Naylor, who directs them towards honest Ted Case, another retired officer and he gives them evidence of Ackroyd's involvement with Chapman. This in turn leads Gerry back to Bryant and McCabe and arrests are made, followed by recrimination, chicanery, a funeral and a departure.

Detective inspector Frank Paterson joins the team to reopen a thirty year old bullion robbery after he has tracked down the getaway car. Two guards died, allegedly at the hands of vicious Michael Denby - the fourth man in the robbery, who, unlike the other three, was never accounted for and is still at large. Frank and Sandra do not get on and she is sceptical when he claims that John Felsham, now a deputy assistant commissioner, was a bent copper who tipped Denby off, Felsham telling her that Frank has long held a personal grudge against him. However Felsham arrives unexpectedly at a back street pub once used by Denby where Frank and Gerry are following a lead and Frank fights him. As a result Felsham wants UCOS disbanded. But the team are determined to carry on and, backed by Strickland, they make sure that they get their man.

Pullman's mother has a stroke, and this event leads Sandra to start asking questions about her father, but she ends up losing her trust in the team when she discovers they have withheld information about her father from her. The revelation that he committed suicide while under investigation for corruption causes the detective to doubt all she took for granted, but she tries to set her feelings aside when she is asked to look into the death of a circus ringmaster who burned to death in his caravan, leaving only his feet behind.

Sandra does not believe recently released paedophile John Davies when he owns to killing 5-year old Yasser Gorton-Blackledge, who disappeared after going on a Free Palestine march with his left wing parents Anne and Fred in 1985. Now divorced, Anne still campaigns for liberal issues but Fred is a hard right reactionary and misogynist. Davies eventually admits to Sandra that he was bullied into confession by Anthony Vernon, a violent disciple of Fred who once hoped to make his name in journalism from Yasser's case. Another ex-activist, kindly nurse Gillian Withall, adopted a little boy at much the same time that Yasser disappeared and, as Gerry and Brian read through the files MI5 compiled on the Gorton-Blackledges it becomes more than likely to them that Yasser is still alive.

The UCOS team investigates the death of Eric Trimble, a soldier who was beaten to death in 1991. Their informant tells them that he and Eric, while still in the Army, were part of secret medical experiments that left the survivors paranoid. Their attempts to investigate those experiments come up against a military establishment that puts every possible in their way, including a visit from MI-5. As the investigation continues however, they discover several other possible motives including the fact that Eric was a bully and also gay. The fact that he is black also makes race a possible motive. Meanwhile, Brian continues to struggle with his alcoholism.

On New Year's Eve 1999 progressive mental health campaigner Greg Collins was murdered and now the discovery of his diary is found, chronicling his fear of his likely fate. The team interviews his colleagues including Toni Pembury, who tells them that Greg was battling a drugs company, and Samia Khan, now a peeress, who fell out with Greg after leaving his mental health charity to set up one of her own. Then they are ordered to halt the inquiry, supposedly in the wake of the mishandled Henway case. When Greg's journal goes missing they must work unofficially to solve his murder - and work fast since UCOS is threatened with being disbanded.