A Man of Conviction

The robberies are being run from inside, so Bulman has to go inside to find them. The assignment puts him among men doing time, and the episode makes the most of the setting. But a prison is a small, sealed world where everyone watches everyone, and a stranger cannot simply blend in by being polite. Bulman's cover requires him to be harder and quieter than his natural self, and Don Henderson is good at that subtraction, playing a man who has to remember not to be himself.

Murray Smith wrote it, Tom Cotter directed, and the hour is at its strongest when it leans on the texture of the place: the routines and hierarchies, the conversations that mean more than they say. The mystery is solved by watching rather than chasing, which suits a detective who has always trusted his eyes. It is the rare episode where the location does half the writing. Thorley Walters' Bill Dugdale and Mark McManus' DCS Jack Lambie circle the edges of the operation, the familiar faces of a world that will not quite let Bulman go.

The title is a pun and a half. A man of conviction is both a man doing time and a man with principles, and the episode gently makes the point that the two are not always different things. The men Bulman is investigating are convicted in both senses of the word, and the show does not need to underline the irony.

The prison setting does what the show's best locations do: it concentrates the drama. There is nowhere to run, which means the case has to be solved by patience, and the episode watches very well. The undercover work is the meat of the hour, and the show gives it room. Bulman gets his men. The principles survive the experience, which is the conviction that matters.