After a 30 year old time capsule is unearthed, a cassette tape inside reopens the unsolved murder of a 16 year old girl. Part of the tape includes a state secret; words from a speech written for the queen during the Cold War. Gerry attends his furture son in law's stag party, and Sasha has her first romance since her divorce from Ned.

After an amateur sleuth is murdered, a photo of Danny is found at the scene. It trns 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. Sasha deals with an overbearing fellow officer, and Gerry moves in with Steve for a spell.

When a teenage boy trrows a brick onto a busy highway, DNA on the brick provides a link to the killer in the 2010 murder of a 55 year old interpreter and chess enthusiast. Steve brings his dying father to a hospice in London.

After the 2009 death of a pub landlord in a fire, his live-in barmaid, an illegal Turkish immigrant, disappeared. When the Turkish woman is arrested,UCOS re-examines the events surrounding the landlord's demise. As the team looks for answers, Sasha enters them in a local sports competition.

Traces of blood on a Roman sword are linked to an unidentified, headless corpse found in 2008, Taking up the unsolved case, the team enters the world of Roman battle re-enactors. Just as Danny starts having feelings for someone new, he learns that his wife might be discharged from the secure hospital where she has spent several years.

When the discovery of a film critic's body in a sewer relates to the unsolved murder of an artist 20 years earlier, Sasha must work with her ex again. Ned's team tackles the latest crime, while UCOS digs into the cold csase. Danny's knowledge of underground London may be the key to solving both.

An 80 year old woman with dementia walks into a police station to report the 60 year old murder of her husband, a London bobby. The official report says he fell into the river, but the team's investigation uncovers old secrets, After Steve's teenage son is arrested for buying weed, Steve encounters the ex-wife he hasn't seen in 10 years.

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 anti-nuclear prostests of the 1980's. Sasha had dinner with Ned, who's angling for a reconcilliation

When a new witness comes forward with information about the violennt murder of a brilliant young doctor, the team uncovers evidence of her unhappy past: a possible stalker, a tutor who was suspiciously close, and the husband of a patient who died under her care. Dan is depressed because his daughter has left home for university

During a visit to his old neighborhood, Gerry meets a childhood friend who needs his help. Ralph Paxton's grandson, a talented young architect, died in a fall from an abandoned building; Ralph is convinced he was murdered. Meanwihile, Gerry objects to his daughter's fiancé, and Sasha is forced to work wtih her ex-husband, Ned Hancock