DCI John Luther returns to investigate a twisted fetishist who is murdering women in a horrific echo of an unsolved case from the 1980s. Meanwhile, Ripley is introduced by embittered Erin Gray to creepy, "unretired" DSU George Stark, who is obsessed with proving that Luther has been taking the law into his own hands. Unaware of the looming threat, Luther considers a new romance with Mary Day after they literally bump into each other in the street.