Mask of Sanity (1)

James Jenson walks out of a psychiatric unit twenty years after three murders he apparently committed out of uncontrollable anger. Two days later, the wallets of his victims arrive at a relative's house. That's the opening move of Mask of Sanity, and it's a good one: either a killer is signalling he's starting again, or someone is making very sure the world keeps blaming a man who may have taken the fall for somebody else.

That second possibility is what pulls the Cold Case Squad back in. The original case was closed on the tidy theory that the murders came down to anger management, which is the sort of explanation that sounds clinical and explains nothing. Boyd and the team now have to pull twenty years of evidence apart and ask whether the psychiatric file was ever the truth or just the most convenient version of it. The wallets are doing double duty as plot device and provocation, and the episode uses them well; whoever sent them knows exactly what panic they'd cause.

Trevor Eve is DSI Peter Boyd, with Sue Johnston's Dr Grace Foley, Wil Johnson's DI Spencer Jordan, Félicité Du Jeu's DC Stella Goodman and Tara Fitzgerald's Dr Eve Lockhart. Nicholas Beveney plays James Jenson, a role that asks for stillness more than menace, and he gives it that. Paul Ritter is Alan Pierce, James Fox plays Dr Bruno Rivelli, and Jemma Redgrave and Martin Marquez are Sophie and Harris Wall.

Laurence Davey, Declan Croghan and Barbara Machin wrote it; David Thacker directs.

Part one is mostly doubt, and the doubt is the entertainment. Every certainty the original investigation rested on gets turned over, and the show is honest about how much of the old file was assumption wearing the uniform of evidence. Whether Jenson is a monster, a scapegoat or both is left hanging where it belongs.