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 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.