Winner Takes All

"Winner Takes All" is written by Robert Holmes, the greatest of Doctor Who's writers, and it is a proper little puzzle-box — a computer thriller set at Jersey's first computer convention, in which the computers are the least of it. Jarvis McLeod, a wealthy businessman with a house full of gadgets, receives a message on his home computer: "McLeod. Buy your headstone now." Bergerac, dragged away from a game of strip tiddlywinks with Susan, is called in to find out who is threatening him and why.

Ian McNeice plays McLeod with a blustering, gadget-proud vanity that makes him an easy man to dislike; Ruth Goring's Monica, his wife, is cooler and more watchful. The suspects assemble neatly: McLeod's former partner John Logan, who unsuccessfully sued him for breach of copyright and who once shared both the company and Monica; the unhappy creditors of McLeod's collapsed firm King Computers; and the convention itself, a four-day circus organised by Hungerford, who has booked hotel rooms and sold them on at a profit. The threats escalate — a fence cut, brake pipes severed, the family dog poisoned — and the pattern is almost too neat.

Holmes' script plays fair with the reader. The dog didn't bark; the meat was wrapped; the car accident was minor; and Logan, the obvious suspect, is caught with gelignite in his car and an alibi that involves Deborah, of all people. The real killer, of course, is the person no one suspects: Monica, who designed the games, who poisoned the dog that once belonged to her and Logan, and who would inherit her husband's company with no competition. The bomb in the projector that kills the man speaking in McLeod's place is her work; the message on the screen is her signature.

The finale is a neat, quiet piece of deduction: Bergerac realises Monica asked to meet Logan, works out she sent the threat on a timer, and defuses the bomb in the computer room seconds before it is meant to go off. Robert Young directs with a brisk, contemporary sheen that suits the computer setting. The closing line — Susan remarking that you can learn anything from books — almost -is the series at its most sly. A sharp, well-made hour that shows the fifth series could do modern, gadget-driven crime with a classic whodunit's bones.