Private Detective Cormoran Strike is visiting his family in Cornwall when he is approached by a woman asking for help finding her mother, Margot Bamborough, who went missing in mysterious circumstances in 1974. 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.