The Mousetrap
Agatha Christie
 The play is set in the Great Hall of Monkswell Manor. The time – the present (1952). ;Act I :Scene 1 – Late afternoon. A woman has been murdered in London. A young couple, Mollie and Giles Ralston, have started a guest house in the converted Monkswell Manor. Their first four guests arrive: Christopher Wren, Mrs. Boyle, Major Metcalf and Miss Casewell. Mrs. Boyle complains about everything, and Giles offers to cancel her stay, but she refuses the offer. They become snowed in together and read in the newspaper of the murder. An additional traveller, Mr. Paravicini, arrives stranded after he ran his car into a snowdrift, but he makes his hosts uneasy. :Scene 2 – The following day after lunch. The imposing Mrs. Boyle complains to the other guests, first to Metcalf and then to Miss Casewell, who both try to get away from her. Wren comes into the room claiming to have fled Mrs. Boyle in the library. Shortly afterwards, the police call on the phone, creating great alarm amongst the guests. Mrs. Boyle suggests that Mollie check Wren's references. Detective Sergeant Trotter arrives on skis to inform the group that he believes a murderer is at large and on his way to the hotel, following the death of Mrs Maureen Lyon in London. When Mrs Boyle is killed, they realise that the murderer is already there. ;Act II Ten minutes later, the investigation is ongoing. Each character is scrutinised and suspected. Mollie and Giles get into a fight, and Chris Wren and Giles argue over who should protect Mollie. Suspicion falls first on Christopher Wren, an erratic young man who fits the description of the supposed murderer. However, it quickly transpires that the killer could be any one of the guests, or even the hosts themselves. The characters re-enact the second murder, trying to prevent a third. At last, Sergeant Trotter assembles everyone in the hall with the plan to set a trap for one of the suspects. The murderer's identity is divulged near the end of the play. In a twist ending, it is revealed that the murderer is Sergeant Trotter, who is not a policeman at all but an insane killer seeking to avenge his brother's death; that Miss Casewell is actually his sister who came looking for him; that Mollie Ralston taught the children as students when she was a teacher; and that Major Metcalf is, in fact, an undercover police detective, looking for the murderer. The uncommonness of the twist ending comes from playing with the basic whodunnit formula, where the cliché is that the detective solves the crime and expose the remaining plot secrets.