End Game (1)

Most detectives dread cold cases. Boyd gets this one delivered by a woman with a professional interest in murder. Linda Cummings, the serial killer he put away, asks him to investigate two deaths at her psychiatric hospital, and the whole thing stinks from the first phone call. She wants him to dig into secrets that were presumably best left alone. That is precisely why he goes.

The whole setup is a trap with the jaws held open. The hospital is the kind of institution this series loves, all locked wards and staff who know more than they say. Cummings offers Boyd two murders to solve and refuses to say whether they are genuine cases or elaborate games. But she knows her man. He cannot resist an unsolved death, least of all one handed to him by the woman he caught. Around him drift Jackie, Dr Mohammed, David O'Neal and Ellen, and every piece of evidence could have been placed for him to find. Ruth Gemmell plays Cummings with a polite, patient menace, and the question of whether she is for real or simply amusing herself keeps the whole hour humming.

Barbara Machin, Daniel Percival and Andrew Holden wrote it, with Percival directing. The regulars are all present: Trevor Eve's Boyd, Sue Johnston's Grace Foley, Tara Fitzgerald's Eve Lockhart, Wil Johnson's Jordan and Stacey Roca's Katrina Howard, with Gina McKee as Jackie, Alexander Siddig as Dr Mohammed, Nathan Constance as David O'Neal and Michelle Tate as Ellen.

The trick of the episode is that Boyd's vanity is part of the machinery. Cummings knows exactly which buttons to press, and the danger is not really the killer at all. You watch Boyd walk into it with your hand over your eyes. It is the story she is telling him, and how much of it he wants to believe.