After an attempt to rescue a kidnap victim the officer in charge, Supt. Sandra Pullman, who also shot a dog during the raid, is reassigned. DAC Donald Bevan puts her in charge of UCOS, a new unit focusing on unsolved cases. There are no resources available, but Sandra is authorized to hire retired detectives and turns first to her old boss and mentor, Jack Halford, who quickly signs on. Together, they interview a number of ex-policemen and settle on Brian Lane, a reformed alcoholic who retired after a prisoner in his custody died, and Gerry Standing, who seems to know as many criminals as policemen and who won't hesitate to cut corners if it will get him a result. Their first case is that of Roddy Wringer, who is released after 21 years in prison when one of the officers on his case is found to have been corrupt. Bevan is convinced Wringer is guilty and makes it clear that he expects Sandra to prove that. As the investigation progresses, however, it appears that Wringer may not have committed the murder that put him in jail and that the investigating officer knew that but withheld evidence.

The team investigate the murder of a policewoman 17 years ago, but what is Sandra's connection, and what secrets from her days at Hendon are revealed?

Sir Tim is Surveyor of the Queen's Pictures. He discovers that some of the pictures in his charge are fakes. But they never used to be. Was his predecessor making money on the side?

The team investigate the murder of a young peace protester, killed near a nuclear base in 1984. Was it a cover-up?

A 10-year-old boy is killed on a golf course. Some 20 years later, the team investigate but face obstruction from a snobbish golf club committee, who struggle to keep women out of the bar and to protect the memory of a Falklands war hero.

The team investigate the disappearance of an attractive young mum and her six-month old son in the 1970s. They also have to submit to a physical and psychological assessment.

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.

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.

Sandra is approached by a tabloid editor who believes that former TV cookery queen Kitty Campbell poisoned her husband Bertie. Kitty obviously denies this but the Campbells' former assistant reveals that Bertie was a closet gay, much to Kitty's disgust. Esther Lane is bedridden after accidentally cutting herself while washing dishes and Brian realizes the extent to which he depends on her, the more so as, whilst watching archive film of the Campbells, she discovers the key to the mystery.

A friend of Jack Halford has a diamond that would appear to have been stolen.

The UCOS team investigate the kidnapping of two 10-year-old boys over twenty years ago. Brian thinks it may be related to a current spate of kidnappings. What they know is that two boys, Daryl and Alan, were taken while fishing at an old pit. A few days later, they managed to escape unharmed, but the police never made an arrest in the case. One of the survivors agrees to undergo hypnosis, which reveals some additional clues. They soon learn that others fishing at the pit were either threatened or attacked over the years, including a champion fisherman who had held the record for catching the largest carp. As Brian spends more and more time by himself fishing at the pit, his wife, Esther, seeks Sandra Pullman's advice.

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.

DS Pullman decides to reopen one of her old cases involving the death of Nancy Murray in a car crash. Pullman is convinced that Nancy's husband, Stephen, introduced a mechanical fault and was out to get his wife because of an alleged affair she was having. Jack thinks the threats must have come from another woman, while Gerry thinks that she died for a simple reason: she was a woman driver. The team learns that Nancy was seeing a male prostitute twice weekly, and blackmail becomes a real possibility. The solution to the murder, however, is to be found by examining basic human needs and emotions.

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 team revive a 30-year-old investigation into animal cruelty when a dog is found butchered on Hampstead Heath. The original investigation focused on John Fletcher, who was the press officer for The Human Liberation Front, an organization that was set up to counter the animal rights movement but no longer in existence. They seek advice from James Farlow, the animal control officer at the time, but have few leads. They determine that the killer may actually have wanted to harvest the animal's vital organs. Meanwhile, Jack is feeling ill and is hospitalised with some unknown ailment.

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.

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.

Jack and the team reopen the investigation into the undetermined death of an elderly woman, partly consumed by her hordes of cats, whose decision to leave her estate to her cats sparked a family feud. When the deceased's pets die, her money and property comes back up for grabs, leaving the detectives with no choice but to get to the bottom of her mysterious demise.

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.

The team reopen a 20-year-old case when a camera and film belonging to a photographic lab assistant murdered in 1987 are found in a Soho pub toilet. New evidence leads the detectives into the dark underside of the modelling world and to the door of a professional footballer. Meanwhile, Brian's erratic behaviour takes an alarming turn and Gerry is less than happy when his daughter Emily joins the team and looks to Sandra as a role model.

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.

A new witness comes forward in the murder of 18 year-old Justin King. Justin had been missing for several months before his body was found but the pathologist determined he had been dead for no more than a week. He had also been tortured. Heidi, now 18 herself, tells the police that Justin had been living on a commune and that she saw him a week or so before he died. From all accounts, Justin simply left the commune one day and was never seen again. Sandra isn't buying it however and believes one of the commune's residents was involved in his death. Brian meanwhile is struggling with his alcoholism and may be looking for help.

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.

Gerry has a run-in with David Fleeting who he practically accuses of being a pervert before realizing the man is desperately looking for his wife. The only complication is that she is supposed to have died 18 months previously. Fleeting insists that he recently saw her in a crowd and is now convinced that the body of the car crash victim identified by his sister-in-law - he was away on business trip at the time of the accident - was that of someone else. Sandra isn't too keen but agrees on seeking an exhumation. A DNA test reveals the dead woman to be a Turkish immigrant who was reported missing around the same time Fleeting's wife was supposed to have died. As the investigators soon learn, the two cases are connected and not all is as it seems at first glance.

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.

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.

Some years after her wealthy father died of a heart attack confronting an intruder - who fled empty-handed - Vicky Anderson asks Sandra and the team to intervene, since clairvoyant Sebastian Carter, having supposedly communed with the dead man, claims he knew the assailant. Sandra is sceptical, feeling Carter is in league with the would-be burglar and using Vicky to get at what he wanted that night. The trail leads to Penny, Vicky's adopted sister, taken in by Anderson after her father died in prison serving a sentence for fraud, and Simon Beswick, the cell-mate, who tells the team he thinks Anderson was also guilty of fraud and the burglar a double-crossed partner-in-crime after the spoils. Sandra is still unsure if Carter is an accomplice or an innocent dupe though, when the case is closed, his interpretation of her father's feelings brings her closer to half-brother Tom.

In 2007 lecturer Richard Symes fell off a roof at the university where he taught and died. An open verdict was recorded but Brian feels that suicide was unlikely as Symes had just taken a whole load of books out of the London Library. Brian loves going undercover at the library ("It smells of books") where he is befriended by the Urquharts, a couple of elderly lecturers who knew the dead man. Symes' widow Paula tells Sandra her husband was regarded as a dinosaur and sacked by vice-chancellor Ventham,but he claims that Symes was stealing books from the university library to sell in Paula's shop,which Paula admits. Her young lover Tim was also part of the racket. Brian works out that the Urquharts are trying to locate one of the books Symes stole,a priceless first edition which he hid somewhere in the London Library. But several other interested parties are also after it - including the murderer.

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.

The team investigates the murder of an anonymous tramp on a London Underground train 15 years earlier.

The UCOS team are drawn into a world of immigration, Albanian gangs and family feuds when they reinvestigate the death of an unidentified man.

Some past memories and feelings are stirred up when Detective Superintendent Sandra Pullman is reunited with an old flame, DCI James Larson.

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.

Still missing Jack, the team reopens the disappearance five years earlier of PE teacher Jason Bowe when human remains are found at Peregrine Manor school, where he taught. Of the staff only support worker Helen Hanley is helpful. Stuffy Latin teacher Archie Millgrow argued with Jason about his over-familiarity with pupils whilst former student Eleanor, now the school secretary, and sports jock Oliver believed Jason was having an affair with pupil Melissa. Brian is more concerned that, despite falling intake numbers, school finances are surprisingly healthy and suspects Jason stumbled upon a plot by which wealthy donors subsidised the school in return for favours from old boy Geoffrey Parks, MP, Melissa's father. Then one of the suspects makes a confession but the team is not convinced and believes they are covering for someone else.

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.

When junior tennis champion Alice Kemp fell to her death from a balcony in 2010, it was assumed she killed herself as she had lost a crucial match but now a cleaner recalls hearing raised voices just before the death and the case is reopened. Alice's agent, Anthony Marshall, claims he lost a valuable client but admits Alice was considering a change of representation whilst Victoria, Alice's mother, tells the team that David, her estranged husband, a gambling addict, had visited Alice before the fatal match. He admits that he was betting against her for money and asked her to lose the march but denies any foul play. Fawn, the player who beat Alice and took her place as Number One, was nonetheless good friends with her and helps the team find the person responsible for Alice's death though Brian is less successful in trying to get his dog in with a model agency.

Ten years earlier the charred corpse of young poet Sean Doherty was found in the scrapyard of Turkish drug-dealer Mehtin Topal, though Topal was not convicted of the killing. Now the case is reopened and the team interviews Sean's contemporaries, including his tutor and lover Sarah Powell and ex-flatmate Luke Oswald, now a media darling. Unlike cynical Gerry, Brian is taken by the world of poetry but Sean's brother-in-law Eoin also claims that Sean had gangster connections. CCTV provides an unexpected clue to the solution of the case, fuelled by Brian's poetical observations and leading to a surprising discovery.

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.

Gerry and Brian end up on an orange farm from where they hitch a lift with a biker group back to Gibraltar and tell Sandra of the connection between Fletcher and Truman and the fact that Danny Bossano's father Levy met Fletcher just before he died. Levy is tight-lipped as to why he has thirty grand in the house, Truman explaining to Sandra that the thirty grand was actually Fletcher's casino winnings. Meanwhile Gerry and Brian discover that Danny drew many pictures of his friends, the sons of soldiers, one of whom was a young Sinclair, who describes Danny's accidental death. Levy then unmasks Christian's killer who had been paying him to keep quiet. Back home Brian faces his tribunal but Embleton, the man he blames for Anthony Kaye's death in custody, drops charges against him and he is exonerated. However Brian secretly tapes a confession from Embleton as to what really happened and gives the tape to Kaye's mother.

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.

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.

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 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.

The UCOS team investigate the kidnapping of two 10-year-old boys over twenty years ago. Brian thinks it may be related to a current spate of kidnappings. What they know is that two boys, Daryl and Alan, were taken while fishing at an old pit. A few days later, they managed to escape unharmed, but the police never made an arrest in the case. One of the survivors agrees to undergo hypnosis, which reveals some additional clues. They soon learn that others fishing at the pit were either threatened or attacked over the years, including a champion fisherman who had held the record for catching the largest carp. As Brian spends more and more time by himself fishing at the pit, his wife, Esther, seeks Sandra Pullman's advice.

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.

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.

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.

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.

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.