What's the Strength of This?

DI Harry Naylor is caught moonlighting for a security firm, and the reason breaks your heart: he's raising money for the treatment of his terminally ill wife, Joyce. But the force doesn't do context. Graves suspends him and starts disciplinary proceedings, and Clark, who has watched Naylor carry him for two seasons, steps in to vouch for a man facing a tribunal. It's the loyalty episode the series has been building toward, and it lands harder because the loyalty is being spent on a dying woman's care.

J. C. Wilsher wrote it, Robert Bierman directed, and the episode is a knot of small corruptions. Officers called to a sudden death are accused of stealing from the scene, and a local burglar confesses, but Clark doesn't believe the man wasn't coached into the admission. Naylor's boss is seen reporting to Deakin, and Naylor's extra wages look less like a bonus than a bribe. When Clark finally confronts Deakin, the trail runs through an inoperative alarm and a burglary at a solicitor's office that Mo discovers was never even reported.

The twist in the tail is Berridge. There's a deniable link between Angela Berridge and Deakin, and the episode lets it sit there, unremarked, the way the best serials leave their threads. Robin Ellis, forever Ross Poldark to a certain generation, plays Donald Berridge, and the name alone tells you where this is heading.

Naylor keeps his job, for now. But the stain stays on the department's edges, and Clark has spent the episode learning something he didn't want to know: the people he trusts are the ones Deakin uses. The disciplinary hearing gives the regulars their best shared scenes in a while, everyone watching a good man squirm for reasons that have nothing to do with justice. The episode knows the system it's describing, and it describes it without mercy.