SIEUTH IS BOTH a suspenseful British thriller, and a clever satire that up-ends all time honored deadbody-in-the-rose-bed conventions. The impoverished Italian, desperate for money to support his spendthrift lover, doesn't ever steal anything. The aristocratic husband, bearing the cross of cuckoldry on his corpulent frame, shoots him squarely through the head but no one ever dies. When the crusty, provincial detective scrapes dried blood from the bannister, he really isn't looking for a murder victim. With the mystery at the brink of solution--and this is the biggest bluff of all--it appears there was no crime. This path of deception and confusion makes an evening of humorous mystery, and any selfmade detective has a good chance to discover the truth three or four times before the script oveals it.

The suspense and humor wane only when Sleuth's ambitious author. Anthony Shaffer, overshoots his thematic boundaries. Shaffer tries to make Sleuth a philosophical discussion of conflicting honesty and fantasy in his characters' self-images, but this serious speculation is distinctly out of place. At its best, from the writings of Arthur Conan Doyle to Agatha Christie, the genre has recounted imaginary adventures of imaginary people, largely, ignoring the problems of real life. Fortunately the play's simplistic message about seeing ourselves as we really are rarely interferes with the progress from clue to clue.

Michael Allinson largely supports the play in his lead role as the successful mystery writer Andrew Wyke. Allinson struts around the stage like a long-legged bird secure on its own rocky turf, waving his arms and laughing from his belly while populating his imagination with his ace detective St. John Lord Merridew and a host of artful villains. Wyke's sixteenth century country house, the play's only set, is filled with bizarre paraphernalia. Among its pillars, arches, and cluttered bookcases sits a paper-mache automaton with a toothy smile. It laughs uproariously when Wyke activates it after each of his silly puns.

Wyke has the opportunity to actualize a macabre mastery when he invites Milo Tindle the lover of his wife Marguerite, to his isolated house late one evening. Wyke convinces Tindle that his modest income as a travel agent--best known for 'Tindle's Tours to Jamaica"--will not keep Marguerite living in the style to which she is accustomed. He persuades Tindle to steal a cache of jewels worth 100.000 pounds hidden in the cellar. Tindle will keep the tiresome Marguerite permanently, and Wyke will collect the insurance. Together they plan the artificial robbery, carefully obeying Wyke's insistence that it be a "true crime of the thirties, with all the amateur aristocratic quirkiness." The game proceeds as both Wyke and Tindle trick each other into more and more flamboyant dissemblance.

THE PLAY'S CONVOLUTED DECEPTIONS sometimes surpass the cast's abilities. Curt Dawson's Tindle cannot maintain the timing and exuberance necessary to keep the robbery interesting, nor does he ever realize the vengeful anger his part demands. An incongruous airiness in Dawson's voice and the stiffness of his movements force Allinson to provide all the game's vitality, but it is difficult for him to do it all alone. Similarly Philip Farrar's Detective Doppler is lugubrious and meticulous without being convincing.

Despite these flaws the play's ornate, Gothic-novel quality makes it fully enjoyable. It twists down the dark tunnels of crime with the special mock-seriousness that delights every mystery lover, exploiting all the best conventions on its way. In the best moments I was convinced every door hid a secret corpse, and that every goodness contained a little folly.