Substitute (2)

The second half of Substitute is the darker of the two. The team finally works out what the people at the centre of the case have been smuggling, and it is worse than anyone wanted to believe: human body parts, harvested from smuggled illegal aliens and sold for a handsome profit on the black market. The episode keeps the mechanics off screen, which is probably wise. The bare fact is enough to sit with.

The real engine of this half is Eve Lockhart. Her trust in her boyfriend proves spectacularly misplaced, worse even than Boyd had allowed for, and the rescue that ought to follow turns into something more frightening. She gets out of the place where she is being held. But Stefan Koscinski has no intention of letting her go quietly, and what follows is a pursuit that runs through the whole episode. Tara Fitzgerald carries it well, and Joseph Mawle makes Koscinski a properly unnerving presence, the sort of quiet threat that stays with you after the credits.

The writing is shared by Barbara Machin, Edward Bennett and Ed Whitmore, with Bennett also directing. The usual team are all here: Trevor Eve's Boyd, Sue Johnston's Grace Foley, Wil Johnson's Jordan and Stacey Roca's Katrina Howard, backed by Zelda Tinska as Olena Kuzmich, Andrew Byron as Georg, Eliza L. Bennett as Briony Havers and Nigel Lindsay as Devlin.

It is solid, grubby procedural work, and the series does this kind of thing well. The investigation stays grounded while the personal threat quietly grows, and the balance between the two is why these episodes still hold up. Eve is not simply a damsel waiting to be rescued. She escapes on her own steam, and the show lets her. That counts for a lot, and in a series this fond of putting its people in danger, it is good to see one get clear.