The body of a young man is discovered face down in a river by Thrunton Woods, bludgeoned to death. But with no ID on the body, tracing the victim's identity proves difficult for DCI Vera Stanhope and her team. Vera is forced to make headway with the only clues they have: a mourning ring worn around the young man's neck, needle marks on the body, and a drugs wrap with a distinctive stamp - 'Dark Angel'.