Private Detective Cormoran Strike is visiting his family in Cornwall when he is approached by a woman asking for help finding her mother who went missing in mysterious circumstances in 1974. Strike has never tackled a cold case before, let alone one forty years old. But despite the slim chance of success, he is intrigued and takes it on. As Strike and Robin investigate Margot's disappearance, they come up against a fiendishly complex case with leads that include tarot cards, a psychopathic serial killer and witnesses who cannot all be trusted. And they learn that even cases decades old can prove to be deadly . . .