East Yorkshire: Single mum Alice Lake finds a man on the beach outside her house. He has no name, no jacket, no idea what he is doing there. Against her better judgement, she invites him in to her home. Surrey: Twenty-one-year-old Lily Monrose has only been married for three weeks. When her new husband fails to come home from work one night, she is left stranded in a new country where she knows no one.
Criminal investigating officer Hanne Wilhelmsen considers the possibility of a serial killer as she tracks down a series of numbers written in blood appearing on walls all over Oslo.