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.

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.

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.

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.

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.

The blood-stained clothes of Simon Belgrade are found in Epping Forest, where he disappeared five years earlier whilst out for a run. Frank Miles, Simon's father-in-law and employer, has a history of violence and his daughter Becky, who was heavily pregnant with Simon's child when he disappeared, seems scared of him. She does not want to believe her husband is dead and nor do his mother Eliza and brother Tim, who portray Simon and Becky as the ideal couple. However Simon's friend Dom and his ex-wife Lois tell the team that Simon and Lois were having an affair, as were Dom and Becky. Simon also had a string of failed businesses behind him and was blackmailing Frank over tax evasion, but with no money taken from his account and no passport it seems unlikely that he skipped the country. An examination of a film showing Dom and Simon's childhood haunts in the forest leads to discovering Simon's fate whilst Dan helps Sandra cope with the anniversary of her father's death.

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.

Gerry is approached by Ralph Paxton, a boyhood friend who became a career criminal and was imprisoned for a jewel robbery. Ralph believes that his grandson, architecture student Jake was murdered by his partner in crime Wayne Pelham because the boy discovered the loot hidden in a tower block due for demolition. After interviewing Jake's brother and his college tutor the team locate Pelham, who informs them that others knew about the hidden jewels. The team eventually end up with two prime suspects, both of whom believing that they were acting out of principle, though one is the killer. Gerry also has to overcome his dislike of the solicitor to whom his daughter Caitlin is getting married.

In 2010 trainee doctor Lydia Dryden was found dead in her flat after visiting Bar 393 night club. Neighbours reported a possible stalker lurking outside the building but her parents, both surgeons, do not recognize him from the Identikit picture. Married Laurence Devlin, another surgeon, denies having an affair with Lydia though it transpires that he is her actual father, which her mother Monica has kept from husband Hugh. Lydia's sister had a drug habit and Lydia was suspected of stealing from the hospital medicine cabinets to help her. then the stalker is revealed, a man whose wife died during an operation performed by Laurence and Lydia. He denies killing her but helps lead the team to the true murderer.

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.

Elderly dementia sufferer Nancy leaves her care home to report that her policeman husband Jimmy, who disappeared in 1956 was actually murdered. Harry Page, an old friend of the couple, reports that Jimmy had gambling debts and got into a fight the night that he died. Sasha takes Nancy back to her old house where she recalls Jimmy's violence and jealousy. A grim secret is discovered in the bedroom wall, in turn leading to the solution of the murder. Meanwhile Steve is called to the police station when his son Stewie is cautioned for minor drug possession, which brings him into conflict with his ex-wife Tricia. They do not part on good terms.

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.

In 2008 body-builder Mark Rix died of a heart attack, seemingly caused by a surfeit of steroids. Now a sword is found in his old lock-up, which decapitated an unknown man just before Mark died. Mark was a member of Imperium, a group re-enacting life in Ancient Rome and Steve and Sasha learn from Imperium members Julia Kane and Tim and Tessa Dugdale that he believed himself to be Marcus Rex, incarnation of a gladiator. Forensic scientist Fiona Kennedy identifies the murder victim as a Romanian gangster who sold illegal steroids and the team deduces that Rix used Imperium's foreign dates to import them. After confessing to Fiona that his estranged wife Sarah is in a secure unit, having tried to kill him and his daughter, Danny goes undercover at Imperium, where he recognizes Julia as another undercover cop. Eventually the team learns the truth about both men's deaths from Julia before Danny goes on a date with Fiona.

Illegal Turkish immigrant Asye Ersoy was working as a barmaid in 2010 but disappeared following a fire which killed the pub's landlord Richard Gibson. Now she has been traced but denies committing any crime. The pub's former pianist Jason claims that Richard was happily married to wife Joanne and she endorses this. Relations with his brother Gavin, a slot machine vendor who wanted to buy the ailing pub, were less harmonious whilst Joanne believes Richard was having an affair with Asye but did nothing about it. The identity of Asye's actual lover and a scam involving the sale of cheap wine, dressed up to appear as of better vintage, are both uncovered before the real killer is unmasked though Gerry and Steve regard the case as a welcome diversion from Sasha's attempts to enter them in a five a side contest.

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.

In 1989 32-year old Charlie Hayes, a stock market trader, fell to his death, a presumed suicide, from his office building near Tower Bridge but a blow up photograph in a retrospective art exhibition reveals a background figure who pushed him.Cash-strapped Steve takes advantage of insider information as the team interviews Charlie's former girlfriend and colleagues, prime suspect being obnoxious Kevin Dodds, whom Charlie exposed as a rapist and the team brings him in. However the rape gives him an alibi for the murder and Danny and Steve discover that Charlie was sacrificed to prevent him disclosing certain anomalies within the company's trading.

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.

In 2002 married Anna and Jim Briggs - who worked for a look-alike agency - were found dead in a supposed suicide pact. Now Anna's phone has been discovered, containing amorous texts to a mysterious lover. The team interviews other look alikes, including Anna's sister and professional rival, Lesley, and ex-soccer star Mikey Bishop, whom Jim impersonated and who says that he met Jim and found him harmless. They also find Mikey's wife Clara is over-protective of her husband as it becomes apparent that he was Anna's lover. a truly bizarre role reversal however proves the key to solving the murders of the two victims.

In 2011 private investigator Dave Hooper was murdered in his office, assumedly the victim of a botched robbery but now his secret notebook, written in shorthand, has come to light though ex-girlfriend Carmen Cresswell could not decipher it. Alison Downing hired Dave to pursue a thieving boyfriend Jason Sharp as did cancer victim Barry Warnock following the burglary of a rare stamp known as the Russian Cousin and worth £40,000. Consequently the progress of the stamp holds the key to the identity of Dave's killer.

The 17 year old skeleton is unearthed of Cheryl Sheekey who disappeared after her pub quiz team syndicate won a fortune on the lottery. In the frame are the quiz team organizer Craig Bentham, his wife Lizzie, who suspected him of an affair with the dead woman, Cheryl's childhood friend Eleanor and her husband Terry, who squandered his winnings and is now on hard times, making him the prime suspect. The team must establish which, if any of them, killed Cheryl as well as trying to set Sasha up with a boyfriend.

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.

In 2002 married Anna and Jim Briggs - who worked for a look-alike agency - were found dead in a supposed suicide pact. Now Anna's phone has been discovered, containing amorous texts to a mysterious lover. The team interviews other look alikes, including Anna's sister and professional rival, Lesley, and ex-soccer star Mikey Bishop, whom Jim impersonated and who says that he met Jim and found him harmless. They also find Mikey's wife Clara is over-protective of her husband as it becomes apparent that he was Anna's lover. a truly bizarre role reversal however proves the key to solving the murders of the two victims.

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.

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.

In 1989 32-year old Charlie Hayes, a stock market trader, fell to his death, a presumed suicide, from his office building near Tower Bridge but a blow up photograph in a retrospective art exhibition reveals a background figure who pushed him.Cash-strapped Steve takes advantage of insider information as the team interviews Charlie's former girlfriend and colleagues, prime suspect being obnoxious Kevin Dodds, whom Charlie exposed as a rapist and the team brings him in. However the rape gives him an alibi for the murder and Danny and Steve discover that Charlie was sacrificed to prevent him disclosing certain anomalies within the company's trading.

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.

In 2011 private investigator Dave Hooper was murdered in his office, assumedly the victim of a botched robbery but now his secret notebook, written in shorthand, has come to light though ex-girlfriend Carmen Cresswell could not decipher it. Alison Downing hired Dave to pursue a thieving boyfriend Jason Sharp as did cancer victim Barry Warnock following the burglary of a rare stamp known as the Russian Cousin and worth £40,000. Consequently the progress of the stamp holds the key to the identity of Dave's killer.

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.

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.

Elderly dementia sufferer Nancy leaves her care home to report that her policeman husband Jimmy, who disappeared in 1956 was actually murdered. Harry Page, an old friend of the couple, reports that Jimmy had gambling debts and got into a fight the night that he died. Sasha takes Nancy back to her old house where she recalls Jimmy's violence and jealousy. A grim secret is discovered in the bedroom wall, in turn leading to the solution of the murder. Meanwhile Steve is called to the police station when his son Stewie is cautioned for minor drug possession, which brings him into conflict with his ex-wife Tricia. They do not part on good terms.