The Mousetrap, London’s longest running play, is vintage Agatha Christie. It was written when she was at the height of her talent, and it exhibits the techniques she always used to provide the audience with all the clues while cleverly concealing the facts. As in Hercule Poirot’s Christmas (1938; also as Murder for Christmas), the murderer is a police officer, or, in this case, a supposed policeman, the least likely suspect. Christopher Wren, on the other hand, is the right age and behaves in a bizarre fashion suitable to a crazed murderer. Miss Casewell, too, is suspect, for while the person who killed Mrs. Stanning is supposed to be a man, Miss Casewell is described as manly. One may recall the significance of this fact in The Mysterious Affair at Styles (1920). Moreover, Miss Casewell owns one of the suspect combinations of dark coat and light scarf.
Once the murderer reveals himself, the evidence becomes clear. No murders occur before Trotter arrives. Mrs. Boyle says that Trotter is too young to be a sergeant, and when her murderer enters the room she is relieved rather than frightened: Only Trotter could evoke that reaction in the atmosphere of suspicion that surrounds the house.
Monkswell Manor itself is typical of Christie’s settings, and the nursery rhyme motif to create an ominous atmosphere recalls One, Two, Buckle My Shoe (1940; also as The Patriotic Murders), And Then There Were None, and Five Little Pigs (1942; also as Murder in Retrospect), as well as the later Hickory, Dickory, Dock (1955; also as Hickory, Dickory, Death) and A Pocket Full of Rye (1953). The surfacing of an old crime to haunt those involved is also a common Christie device, most familiarly used in Murder on the Orient Express (1934; also as Murder in the Calais Coach) and Nemesis (1971).
Here, as elsewhere, Christie presents no overt violence: Mrs. Stanning is killed offstage; Mrs. Boyle is strangled in the dark. Christie’s concern in her plays, as in her novels, is not the horror of the crime—the victims are unpleasant—but the solution to an intellectual puzzle. Nowhere has she created a more engaging problem than in The Mousetrap, which will continue to fascinate audiences as long as actors choose to perform it.