What is the title of the play that has been running in a London theatre based on a book by Agatha Christie for over 68 years?

The title of the play that has been running in a London theatre for over 68 years, based on a work by Agatha Christie, is "The Mousetrap." This play holds the distinction of being the longest-running show in the history of British theatre, having premiered in 1952. Its enduring popularity can be attributed to Christie's clever twists and engaging storytelling. The plot revolves around a group of people stranded in a remote guesthouse, where a murderer is among them, introducing themes of suspense and intrigue.

While other works by Agatha Christie, such as "Murder on the Orient Express," "And Then There Were None," and "Death on the Nile," are also well-known and have been adapted for various media, none match the longevity and ongoing performance history of "The Mousetrap" in London's West End.