Cold Blood

A woman shoots her husband dead after catching him in an affair. Open and shut, Taggart thinks, the easiest case of his career. Taggart is not in the habit of being handed anything easy, and the episode lets him enjoy the illusion for about a quarter of an hour. And then the post-mortem comes back and the whole thing turns inside out: the man was already dead when the bullet hit him. His wife could not have killed him, whatever she believes she did.

From there the episode becomes a different animal. If the wife did not pull the trigger on a live man, someone else did, and someone else was very careful about it. The forensics do the heavy lifting, and the case becomes a question of what exactly happened in that house before the shooting, and who wanted it to look like a domestic tragedy. Dr. Stephen Andrews, the pathologist, delivers the news that dismantles everything, and the look on the room when he does is worth the price of admission.

Glenn Chandler wrote it, Haldane Duncan directed. Mark McManus is DCI Jim Taggart and James MacPherson is DS Mike Jardine, with Diane Keen as Ruth Wilson, Freddie Boardley as Ricki Keenan and Leonard O'Malley as Donny McGregor. Iain Anders is Supt. Jack McVitie, with Mona Bruce as Marjorie McVitie, Harriet Buchan as Jean Taggart, Patricia Ross as DS Laura Campbell and Robert Robertson as Dr. Stephen Andrews.

The twist is the kind that flatters the audience: the moment you hear it, you want to go back and watch the first half again with the new information in hand. That rewatch impulse is the surest sign an episode has done its job. It also turns Ruth Wilson's part from a possible footnote into the whole question of the hour. Cold Blood earns it.