Jigsaw

Regan is sure Eddie Boyse robbed the factory. Boyse is a career criminal, recently out, and he has the job written all over him. It has his signature on it, as Regan keeps telling anyone who will listen, but the one detail that matters is where he was. The trouble is the alibi, and it's a cracker: when the robbery happened, Boyse was with Regan, of all people. The man Regan wants to nick can prove where he was by pointing at the detective trying to nick him. It's the sort of frustration that makes a grown copper want to kick the nearest wall.

Worse, Boyse's complaint that he's being harassed starts to stick, and Regan finds himself answering for his methods while trying to solve a crime he can't even get a fair start on. And the factory job sits there unsolved while the accusations pile up, a man arguing with a puzzle that keeps moving. Every theory he builds has a hole in it, and the hole is himself. Regan hates being wrong almost as much as he hates being patient, and this case forces him to be both.

Tudor Gates and Ian Kennedy Martin wrote it, William Brayne directed. Del Henney's Eddie Boyse is quietly infuriating in the best way, a man who knows he's winning. John Thaw and Dennis Waterman are Regan and Carter, with Garfield Morgan's Haskins, Sheila Gish as June, Ken Parry as Fat Eric and Stephanie Turner as Allison Carter, alongside Jack Woolgar, Richard Hampton and Joan Scott. The night watchman and the headmistress, two small parts, give the neighbourhood its shape.

The joke at the heart of it is a good one: the surest way to prove you didn't do a job in this world is to be standing next to the Flying Squad when it goes off. The episode enjoys that irony without labouring it. Regan's certainty drives him hard, but it isn't infallible. Sometimes it points at the wrong man, and the show was brave enough to admit it.