When Sleuth made its first appearance on the London stage in February 1970, it saw instant success. Moving to Broadway the following November, it won equal praise, even winning a Tony Award in 1971. In the program, audiences and reviewers were asked not to reveal the plot to anyone who had not yet seen the play, for so much of the enjoyment of the play was derived from its almost constant plot twists. Working on the idea of a whodunit, Shaffer instead created the first of its kind: a whodunwhat.
Part of the success of Sleuth comes from Shaffer's misappropriation of the mechanics of the classic murder mystery. More of the success derives from Shaffer's skill at scripting the play. It is filled with baroque language, exaggerated characters, and pompous intellectualism; yet its pretensions are consistently undercut with elements of the farcical, such as Milo's donning of the clown costume Another reason that audiences throughout the world have enjoyed it for years on end is that it is simply pure entertainment. Milo and Andrew match wits with the delicacy of cats inching around their prey. The audience is brought to points of both laughter and terror as the two men play, exchanging roles as cat and then as mouse, until their eventual downfall
Act I opens at Andrew Wyke's country house. The acclaimed mystery writer is working on his most recent novel, when the doorbell rings. At the door is Milo Tindle. Andrew has invited the younger man over to discuss Andrew's wife. Marguerite.
Milo wants to marry her. Andrew does not think that Milo will be able to keep Marguerite in the lavish style to which she has grown accustomed. However, Andrew has a mistress himself, and he is more than happy to have Marguerite taken off his hands. He proposes a plan, which he has already worked out: Milo will "steal" some jewels that Andrew owns and sell them abroad. Thus Milo will have the money needed to support Marguerite; Andrew will be done with his lavish wife and, at the same time, get a hefty settlement from his insurance agency.
Milo is initially suspicious. He is afraid of getting caught, and he is also afraid that Andrew will actually try to frame him for the theft. However, the lure of the money is too great for Miio, and he agrees to the plan.
Andrew has determined that Milo must actually "break in" to the house to make the theft look real. He also wants Milo to wear a disguise. After the two men go through a hamper filled with costumes, Mito ends up dressed as a clown.
Milo goes outside to the shed, where Andrew has left a ladder. He uses the ladder to enter the upstairs gallery through the window. Milo wants to go straight for the safe, but Andrew insists that he ransack the house a bit, to make it look like he is looking for the jewels. Then Andrew takes Milo to the safe, explodes it, and hands Milo a jewel box. Andrew declares that, to make the burglary seem more real, they must enact a scene in which he, Andrew, surprises the burglar, and the two men struggle. He will then be able to give the police a false description of the intruder. The two men begin to toss things around the room and wrestle a bit. Out of his desk drawer, Andrew pulls a gun, which Milo can use to keep Andrew at bay. Andrew shoots several of the items around the room and then points the gun at Milo, while tying him up. Still holding the gun, Andrew declares that he is going to kill Milo He agrees that they have been playing a game all evening, a game in which he kills Milo, and no one suspects him. He tells Milo that he invited him over to create a foolproof murder scene. Milo tries to talk Andrew out of the plan. Andrew resists Milo's plea and pulls the trigger Milo falls down the stairs and lies still.
Act 2 takes place two days later. Andrew is at home when the doorbell rings. He lets in Inspector Doppler of the Constable's office. Doppler is investigating the disappearance of Milo Tindle. Andrew claims to have met Milo a few months ago, but Doppler tells him that Milo had reported that he was coming to see him, Andrew, two nights ago. He also tells Andrew that an eyewitness who was passing the house two nights ago claims to have seen a struggle taking place and to have heard three shots fired from a gun. Doppler then went to Milo's house, where he found the...