The Mousetrap is a murder mystery play by Agatha Christie. The Mousetrap opened in London’s West End in 1952, and has been running continuously since then. The longest running West End show, it has by far the longest initial run of any play in history, with its 25,000th performance taking place on 18 November 2012. The play is known for its twist ending, which the audience is traditionally asked not to reveal after leaving the theatre.