Gerry attempts to clear his name before his enemies catch up with him. Sasha and Steve get Fiona's help to examine the evidence against the clock. Danny takes Gerry on the run as they look for the proof they need to prove his innocence.

Jack announces that he he has decided to leave the team, but before Sandra, Brian and Gerry can question his reasons, Whitehall figure Stephen Fisher shows up with one of his secret cases featuring the unsolved murder of a woman dating back around a hundred years. With only 24 hours to solve it, the team attempt to find time to get to the bottom of Jack's surprising decision and attempt to persuade him not to leave.

Pullman seizes the chance to solve a murder that she believes is linked to her first ever case, and the team start putting together a jigsaw puzzle of suspects from a photograph taken in a London park in the 90s. Eventually faced with increasing pressure to hand over the investigation, Sandra makes a huge decision, which is going to change UCOS forever.

The team reinvestigate the disappearance of two young political activists.

Gerry feels spooked following the discovery of UCOS's latest victim, a policeman, whose body has lain untouched under a basement for the last 30 years. Accusations of police corruption and underhand dealings start to surface causing Gerry to face up to some skeletons in his own closet.

Pullman struggles to keep the boys in line as their chequered pasts begin to be revealed. Halford is determined to nail a vicious criminal who has so far eluded him and in doing so he puts himself in grave danger. Standing receives a surprise visitor which shocks him. Pullman is increasingly frustrated and weighs up an opportunity that could end her time in UCOS.

The team reinvestigate a 30-year-old safety deposit robbery, and they soon find themselves being drawn into a case involving police corruption that threatens the future of the UCOS itself.

The team unlock over three decades of secrets and lies on the Rock of Gibraltar and find the link which solves the murder of a playboy shipping heir from '98 and a young local boy from '82. With both cases solved, they return to England where Lane faces a disciplinary hearing, dragging up a death in custody from his past which threatens his career in UCOS.

As Lane comes to terms with life after UCOS, Esther asks him to help one of her book club friends find her missing brother - but will his nose for the truth get him into further trouble? And how will his former colleagues cope without their most dogged sleuth?

Brian Lane enters rehab to treat his alcoholism, but the rest of the team soon join him.

As the series comes to an end, the desiccated, neatly carved-up body of a butcher who disappeared more than 30 years ago is discovered, leading Sandra Pullman and her boys to pay a visit to Smithfield meat market in London, the original murder scene. It's a pity the butcher is dead, because he has a few questions to answer about why the body of a doctor was found hanging from a meat hook all those years ago at the back of his market stall. It's an episode peppered with revelations. We discover Gerry Standing's very interesting family history - he's descended from French Huguenots and is thus tormented by his colleagues for being a fake cockney, much to his annoyance: "Je suis ang-bleedingglais!" he protests. But it's Sandra who has to face up to a startling personal disclosure that has a direct bearing on the case and also throws a whole new light on her father. For once Gerry, Brian and Jack are left completely speechless.

A woman is sent anonymous emails from someone claiming to know what happened to her husband Phillip Mackenna, a prominent scientist working on cold fusion who disappeared while on a train to Paris. As the team investigate, DAC Strickland receives a warning from Whitehall.

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.

The UCOS team investigate the murder of a young peace protestor, killed at the outskirts of a nuclear base in 1984, and realise that they may be in danger of exposing a Special Branch cover up.

In an attempt to make contact with his late wife Mary, Jack goes to see a clairvoyant. Instead he meets a girl who died in a shipping container in 1982 and has the case re-opened.

Deputy Assistant Commissioner Robert Strickland is the new boss in charge of the Unsolved Crime and Open Case Squad (UCOS). He asks the team to look into the death of David Barrie, a top barrister found in his car in 1980 after being bound and gagged.

In 1996 a beautiful newlywed, was attacked and left for dead. The only thing taken was her wedding ring and she has been in a coma ever since. The man jailed for the crime is now a born-again Christian and is protesting his innocence

The team re-examine the case of Hannah Taylor who was kidnapped from her home in 1992. A body, previously thought to be Hannah's, has just been identified as that of another kidnap victim

Tabloid editor Chris McConnell asks Sandra Pullman to help him prove celebrity chef Kitty Campbell killed her drunken husband Bertie 40 years ago at the height of their 60s TV fame.

Attractive widow and probate assessor Elise Allen asks Halford to find the rightful owner of a large, uncut red diamond, worth £15 million. She found the rare jewel in a flat rented by John Newman who died in 1982.

Luck turns against Standing when he loses a poker game, owing bookie Michael Jacobs £10,000. But Michael offers him a chance to clear his debt by finding out what happened to his dad Joe, who died after being mugged outside Walthamstow stadium in 1983.

Lane indulges his obsession with fishing when UCOS investigates the case of two boys abducted from a fishing lake in 1979, believing it could be linked to a recent spate of snatches near the M25.

The Home Office pathologist asks the team to identify the remains of an unidentified woman, whose remains were found back in 1987. These remains are the only body that he was unable to identify. With his help and that of his attractive assistant, not only must the team identify the body bits, but how she died and who killed her.

When a serial dog killer starts stalking local parks, the team are reluctantly forced into taking on the case.

The future of the team is threatened and without having that to deal with, Sandra has to take drastic measures to prevent Jack from exacting revenge against the man who killed his wife Mary. Sandra also has the added benefit of trying to keep Jack’s actions from shady new recruit DCI Karen Hardwick while working on a 10-year-old murder case.