The Devil You Know

The Devil You Know is a detective story in which the detectives are the alibi. Ken and Margaret are hired to watch Ronnie Hains, whose wife suspects he is having an affair. They follow him and his girlfriend to a boating lake and take a set of incriminating photographs, and Ken finishes the roll with pictures of Margaret. It looks like the simplest case BDI has had.

Then it turns out that a robbery was committed nearby at the same time, and the chief suspect is Ronnie Hains. He tells the police that he was elsewhere, and Ken and Margaret's photographs and statements prove that he was on the lake. Two detectives, Joyman and Pelham, question them at length and with some relish, particularly hostile to Margaret because she used to be one of them.

Suspicion grows when the BDI office at the Plaza Suite is broken into and the only thing taken is Ken's set of photographs of Margaret. Close examination of the negatives shows why. In the background, at the crucial moment, a friend has taken Ronnie's place, leaving Ronnie free to commit the robbery. The affair was never real. The whole thing was a ploy to buy a perfect alibi, and Ken and Margaret were hired to provide it.

To get proof, they offer to sell the negatives to Ronnie and his wife, with the police recording the conversation. Ronnie admits the plan and draws a gun, and Margaret disarms him.

Harry, meanwhile, is away for a gourmet weekend with his friend Roger Evans at a hotel owned by the restaurant critic Gerald Neale. Roger once owned a restaurant, La Camargue, which closed after a run of savage reviews by Neale. He now runs Skool Mealz, a theme restaurant serving food like school dinners, which is a success but not quite what he once had.

A murder-mystery weekend is under way at the hotel, and a fussy, over-eager guest named Rose is searching everywhere for clues. She is really a journalist, looking for evidence against Neale, and she finds it: he has been giving glowing reviews to his own restaurant, owned under his wife's maiden name, and passing off tinned food as his own cooking. Neale is disgraced.

Matthew Bardsley wrote the episode and Bren Simson directs. Paul Freeman plays Hains, John Savident plays Neale, and Jean Alexander plays Rose.

The alibi plot is one of the cleverest in the series. It turns BDI's own method, watching and photographing, into the instrument of the crime, and the clue is in the detail of the negatives. It also gives Margaret the climax, disarming a man with a gun, a reminder that she was a police officer before she was Ken's partner.

The weakness is that the two halves have little to do with each other. Harry's weekend is a pleasant comedy about a critic getting what he deserves, but it could belong to any episode. The main case, though, is sharp enough to carry the hour.