As the radio at Monkswell Manor announces a recent murder, newlyweds Mollie and Giles Ralston are welcoming a motley crew into their guesthouse. Among them are an eccentric architect, a retired Army major, a mysterious traveller, an old woman and an ex-magistrate. As the winter weather barricades them all within, a policeman arrives on skiis to announce the murderer is among the guests - and is going to strike again. Set in the 1950s, The Mousetrap is the quintessential whodunnit.