Ingrid Olsson returns home from a Stockholm hospital to discover a man in her kitchen. She's never seen the intruder before. But he's no threat - he's dead.
Criminal Investigator Conny Sjöberg takes the call, abandoning his wife Åsa and their five children for the night. His team identify the body as that of a middle-aged family man. But why was he there? And who bludgeoned him to death?
Lacking suspect and motive, Sjoberg's team struggle until they link the case to another - apparently random - killing. And discover they face a serial killer on a terrible vendetta . . .