The Mousetrap at the St. Martin's Theatre, London Matinee performances of The Mousetrap are on Tuesdays & Saturdays. The Mousetrap has been thrilling audiences for more than half a century & has entered the record books as the world’s longest running play. Agatha Christie’s masterpiece is a traditional whodunit, with eight separate characters under suspicion after a remote guesthouse becomes the scene of an ugly crime. At the end of each show the audience are sworn to secrecy, keeping the mystery alive for the next performance. The Mousetrap Matinee Tickets offer a great afternoon’s entertainment at St Martin’s Theatre.