Substitute (1)

Every so often Waking the Dead turns the lens on its own people, and Substitute is one of those times. Eve meets a charismatic Eastern European called Stefan Koscinski at a club, and what starts as an affair gets complicated fast, because she runs his DNA against semen from a brutal cold case murder and it matches. Her new boyfriend is a murder suspect, and the episode makes her sit with that.

But Stefan is vague about his past, which is the polite way of saying he is hiding something. Eve puts her professional skills to work on him, and she finds out things she would rather not have found out. Unsure of the next step, she goes to Boyd. He promises support at first. Then the facts settle in, and the two of them want to follow very different paths. A case that divides the team from the inside is harder to watch than any villain.

Barbara Machin, Edward Bennett and Ed Whitmore wrote it, and Bennett also directed. Trevor Eve leads as DSI Peter Boyd, with Sue Johnston as Dr Grace Foley, Tara Fitzgerald as Dr Eve Lockhart, Wil Johnson as DI Spencer Jordan and Stacey Roca as DS Katrina Howard. Joseph Mawle plays Stefan Koscinski, Zelda Tinska Olena Kuzmich, Andrew Byron Georg, Laurentiu Possa Andrei and Eliza Bennett Briony Havers.

The episode gets a lot of mileage out of the personal angle. Eve is usually the one with the clean scientific detachment; here she is the one in the middle of the case, and her judgment is shot through with whatever she feels for Stefan. It is the kind of test the show likes to set its people, and Tara Fitzgerald carries it well. Boyd's support curdles into suspicion, and watching that happen is its own small drama. Eve's distress is the louder one, and she carries it alone.

The title does its work. Stefan is a substitute for something, or someone, and the episode keeps the question open. As opening halves go it sets a personal, uncomfortable trap and leaves the team inside it. The answers will cost somebody, and part two gets to decide who.