The Mousetrap

At the end of this elegant Agatha Christie thriller, the newly uncovered homicidal maniac steps into a sinister spotlight and warns everyone never to reveal his or her identity. The production recently celebrated its 60th birthday and although Wikipedia and Stephen Fry have both blown the murderer's cover, there is a remarkable conspiracy of silence over 'The Moustrap'. The real mystery of the world's longest-running theatre show is not whodunit but, in its currently mediocre state, whydoit at all?

'The Mousetrap's ticket prices are the only element of this show that isn't stuck fast in the 1950s - although the actors' strained RP does make the odd break for the twenty-first century. Otherwise, this is a walking, talking piece of theatre history and - at £39 for a full-price stalls seat - the most expensive museum exhibit in London.

Christie's neat puzzler of a plot is easier to defend. It has defied the inevitably mummifying process of more than 25,000 performances and still possesses an uncanny precision worthy of the mistress of murder's chilling geriatric creation, Miss Marple.

In the 60 years since it premiered, its premise, in which six Cluedo-like middle-class stereotypes are imprisoned by snow in a country house while they try to fathom which of them is a raving murderer, has become a cliché, just as the authorities' response to adverse weather conditions (skiing coppers? In Berkshire?) have become a nostalgic memory.

It's fascinating to glimpse the ghost of Peter Cotes's original 1952 production. But this is sometimes a thin and campy shadow of its former self, whose creaks arise from cliché not suspense. Christie's best thrillers have a psychological conviction and a subtle sense of evil that the current cast, apart from one or two noble exceptions, shelve in favour of xenophobic exaggeration or dullness. Christie's trap still snaps shut but the cat's been away for years, leaving the mice to carry the play.