Untouchable

A pole-dancing club is a strange place for a family dispute, which is probably why the manageress takes hers to the police. She suspects her uncle, Ted Bascombe, of using the club as a front for a prostitution racket, and she says so plainly. The accusation is the easy part. Proving it is where the episode starts to twist.

Joe Robinson makes the call to send Chief Inspector Vickers undercover, which is a bold move and, given recent series history, a slightly insane one. Then the suspicion turns inward. Robinson begins to imagine that his own boss is colluding with the suspect, and the paranoia starts to look reasonable the longer you watch Vickers work. The episode never settles it either way until it has to, which is the correct way to play it. That is the trick of the title: Bascombe may be untouchable, or the man chasing him may be.

Nigel Terry's Ted Bascombe is a fine piece of work, all propriety and menace in equal portions, the sort of man who believes the law is a negotiation. Poppy Elliott's Andrea and Anna Wilson-Jones's Elizabeth give the club its working faces, and the club itself, all lights and desperation, does the rest. The pole dancers get the show's sympathy, which is more than the punters do.

The unit grinds through the case with the usual division of labour. Hutchins and Morgan work the rooms; Johnstone and Parkes chase the paperwork. Cole keeps the sergeant's desk from collapsing, which is its own full-time job. But the episode belongs to the two men at the top, watching each other across a table of unspoken charges.

Alison Hume wrote it, Michael Samuels directed. It is a tight, suspicious hour in which the police work itself becomes the suspect, and it is the better for it. Vickers has never been easy to read, and here the show makes that a feature rather than a frustration.