After being released from jail, notorious paedophile John Davies admits to the abduction and murder of a child 25 years previously. Suspicious of his motives, the detectives reopen the unsolved case in an unusual attempt to prove his innocence, reinvestigating the boy's disappearance while on a demonstration with his left-wing activist parents. Guest starring Adrian Schiller (Being Human) and Samantha Bond (Outnumbered)

When the gun used to murder a talented young boxer 11 years ago surfaces in an armed robbery, UCOS are drawn into the darker side of professional boxing in a case that causes conflict and friction among the team.

The OAP detectives return to investigate a fresh batch of unsolved crimes, beginning with the murder of a palaeontologist at the Natural History Museum. After a bit of digging, the team discover the victim was a respected but outspoken scientist with a knack for rubbing people up the wrong way - and when they discover he was strongly opposed to the museum's sponsorship deal with a large fuel company, the old dogs soon have plenty of suspects.

Amanda Redman stars, with guest appearances from the late Trevor Bannister (Are You Being Served?), Lucy Brown (Primeval) and Natasha Little (Spooks)

After psychologist Samantha Gerson shows up at UCOS to conduct a study on older men in the workplace, she ends up getting a mixed reception. Samantha also wants a favour and asks Pullman to look at her brother's case. Darren Gerson was the victim of a hit and run in May 2006 which left him with a serious brain injury and complete memory loss of anything about his life before the accident happened. Darren now is convinced that he is still a target because of the package he was carrying at the time.

The team looks into the death of a terrorist 30 years previously after his daughter receives an anonymous note claiming he was murdered - an investigation that takes them right back to the Greenham Common anti-nuclear protests.

Meanwhile, Sasha agrees to go for dinner with her ex-husband Ned, which he is hoping will lead to a reconciliation.

When Steve McAndrew's teenage son Stewie is arrested for drug possession, he finds himself face to face again with his ex-wife Tricia as they try to save the boy from a downward spiral. And after a distressed dementia patient escapes her care home to report a murder, the team look into the disappearance of a policeman, possibly murdered but missing since 1956...