While investigating the murder of 55 year-old interpreter Agnes Bradley, the UCOS team get a partial DNA match from a teenage boy who once threw a brick onto a motorway as a dare. They interview the boy to see if one of his male relations could be the murderer, only to discover that his mother was raped and they could be looking for a rapist-turned-murderer. Agnes was a chess enthusiast so Gerry Standing and Steve McAndrew interview members of her local club while Sasha Miller and Strickland investigate leads from Agnes’s working life, where they meet a Chilean diplomat with a possible axe to grind. Steve McAndrew’s elderly father is dying, so he brings him to a London hospice for his last days.