Sacred Trust

Eight-year-old Dylan Nichols is last seen at an amusement arcade. The search turns into a murder inquiry, and the suspects are a grim pair: Ryan Varney, who works at the arcade, and Michael Nash, the recent boyfriend of Dylan's mother. Both are known paedophiles, which makes the inquiry no easier. Nash is arrested, and his use of an assumed name puts him squarely in the frame for the murder.

Janet, meanwhile, has started something with Andy Roper and is already having second thoughts. He is moving too fast for her, and when she tells him so he finds it hard to accept. Rachel's problems are more practical: Dominic's involvement in a car crash stops her taking her sergeant's exam, the exam that was her way out of the ranks. Then Dom's HIV test comes back negative, he sets out to celebrate, and the celebration endangers his own life and whatever is left of Rachel's professional momentum. Gill, for her part, is forced to work with her ex-husband on the case, which is its own kind of punishment.

And the missing boy anchors the hour, though the episode is really about what people do with trust: the family deceived by Nash, Janet uncertain about Andy, Rachel stretched between a brother who keeps self-destructing and a career she cannot get off the ground. None of it is tidy, least of all the ending.

Nicole Taylor, Diane Taylor and Sally Wainwright wrote it, Paul Walker directed. Suranne Jones's Rachel and Lesley Sharp's Janet lead, with Amelia Bullmore's Gill, Nicholas Gleaves as Andy, Ben Batt as Kevin Lumb, Andrew Readman as Chief Constable Rutterford and the squad in support.

A child's death and a mother's trust betrayed, with two detectives who cannot seem to trust their own judgement. The title earns its keep this week.