Aberration

The robbery at the doctor's surgery nearly trips over Barlow and Watt before it has properly started. The two of them are mixed up in it more or less by accident, and the natural reading is a drugs job: break-ins at surgeries usually are, and the stolen pharmaceuticals should lead somewhere familiar. The thief has other ideas, though. The episode is happy to watch the obvious answer fade while the real one waits in the wings, and it falls to PW Det. Con. Forest, the newest face in the squad, to bring him into the open.

But there is a curiosity in the casting worth flagging: the part credited as the Undertaker is played by two actors, Eden Fox and Paul Phillips. Either the man changes his appearance in the middle of the job or the credits are having a quiet joke, and either way it suits an episode where nothing is quite what it says on the tin. Around the surgery sit Doctor Mancroft, played with the expected gravitas by Raymond Huntley, Jameson (Gary Waldhorn), Samuel Tomkins (Norman Bird) and Susan (Marguerite Hardiman), each with a plausible reason to be in the frame.

Elwyn Jones wrote it, Leonard Lewis directed. Stratford Johns and Frank Windsor anchor the proceedings as Barlow and Watt, with David Lloyd Meredith's Evans keeping the street-level work moving.

The result is a patient piece of misdirection rather than a thriller. You are allowed to hold the wrong theory for a while, and the trick works because the episode never cheats: the answer was always in reach. It is a smaller, tidier entry than much of the season, and none the worse for that. Forest earns her moment, and the villain turns out to be cleverer than his own scheme. An aberration, then: a crime out of step with the usual pattern, dealt with by a squad that has seen stranger things by teatime.