May

The episode is called May, which tells you where the heart of it sits. May Holmes is an old friend of Regan's, and when her boy Davey is picked up on suspicion of a violent robbery, the guv'nor finds himself in the familiar position of the copper who knows the family. Davey insists he is innocent. Regan wants to believe him. The rest of the job does not care either way.

But the investigation keeps snagging on the lad's evasions. He is hiding something, and the question the episode keeps turning over is whether his secrets make him guilty or just tangled up in something too big for him. Regan has to pull at the threads without pulling the family apart, which is harder than any raid he will run all year.

The pleasure is in seeing the two Regans at war: the family friend and the detective. Marjorie Yates plays May as a woman who keeps her chin up and her counsel, and Karl Howman's Davey has the stubborn, frightened dignity of a boy who has decided not to tell. The supporting cast is solid, with Geraldine Moffat as Sheila Martin, Brian Gwaspari as the wary Det. Sgt. Cree, Frank Mills as Len Holmes, Tim Hardy as Francis and Jeremy Sinden as the memorably named Det. Con. Feast. Garfield Morgan's Haskins hovers, watching the whole thing with the expression of a man observing a car crash in slow motion.

Trevor Preston and Ian Kennedy Martin wrote it, and Tom Clegg directs with the quiet confidence the story needs. Thaw and Waterman anchor it, Carter doing what Carter does best, which is being where Regan needs him.

It is a quieter, more domestic hour than the series usually attempts, and one of its best character pieces. Regan does not solve this one with a car chase; he solves it by knowing people, which is the older and rarer skill.