Aidan brings his bright 8-year-old daughter Melangell to the retreat centre on the holy island of Lindisfarne to show her the places about which her recently-dead mother Jenny wrote books. There they meet Lucy, a Methodist minister, who is running a course on Northumbrian saints. When Rachel, a troubled teenager whom Lucy had befriended, is found dead on the beach, suspicion falls on one guest after another. The publicity allows Lucy's violent ex-partner, with whom she had served in the police, to track her down ...