The murder mystery or thriller proved to be a staple of the English-language theater throughout the twentieth century: The two most-often-produced plays for more than forty years were J. B. Priestley’s thrillers Dangerous Corner (1932) and An Inspector Calls (1946), The longest running play was Christie’s The Mousetrap (1952). The elements of the successful thriller—clever plotting, engaging characters, and a unique twist—have sustained their appeal with teenagers. In these, the audience competes with a clever detective in deciphering clues presented in a manner of fair play. Shaffer’s Sleuth, however, changed the rules. It used the traditional elements of the thriller but simultaneously undermined them, breaking the rules of logic and forcing the audience to question what is “real” and what is “staged.” Deathtrap joined Sleuth in establishing this new subgenre, called the comedy thriller, in which the playwright “double-codes” the events on stage in an attempt to subvert the standard conventions of the thriller and add a new facet—keeping the audience off-balance. Deathtrap is often taught because, as a part of manipulating the rules, it so clearly defines and explains the rules of creating thrillers. Many comedy thrillers have attempted to duplicate its success, including Nick Hall’s Dead Wrong (1985), Gerald Moon’s Corpse! (1985), John Pielmeier’s Sleight of Hand (1987), and Rupert Holmes’s Accomplice (1990).