London, 1920. When a woman's body is dragged from the Regent's Canal on a freezing January night, eminent forensic pathologist and criminal sleuth Dr Bernard Spilsbury immediately detects foul play. And when a second woman washes up dead under similar circumstances, police realise they are looking for a dangerous predator. Is someone luring lonely spinsters to their deaths through a newspaper Lonely Hearts column? And can they be stopped before they strike again? With time against them, there's only one thing the police can do.