The Mousetrap

Sergeant Trotter (whose real name is Georgie Corrigan) appears outside the window on skis. He introduces himself to Giles (hiding his identity as the killer behind the fake police phone call). Giles lets Trotter in, and Christopher returns. Mrs. Boyle says Trotter looks too young to be a sergeant, a clue that he is not who he says he is. Giles and Trotter leave to put away the skis, and Major Metcalf tries to make a phone call, but the line is dead (it was cut by Trotter).

Once Trotter and Giles return, Trotter begins questioning everyone about the murder in London. He clarifies that the victim was using a false name (foreshadowing the many false names used by the guests of Monkswell Manor) and discusses the victim’s life. Maureen Stanning had been released from prison for the death of a child and criminal neglect of two other children in her care. Trotter says there was a notebook at the scene of the crime with the address of Monkswell Manor in it.

Trotter claims that anyone associated with the case that convicted Maureen is at risk. Mollie guesses that the police are looking for one of the Corrigan children who lived and is seeking revenge, and Trotter confirms this theory (the irony is that he is this survivor). Everyone denies being connected to the case, and Mollie, looking uncomfortable (she was the Corrigan children’s schoolteacher, but this is not revealed until the end of the play), goes to the kitchen.

While Giles shows Trotter around Monkswell Manor offstage, Christopher whistles “Three Blind Mice” and jokes about killing Mrs. Boyle. Metcalf tells him to stop, and Christopher leaves the room. Mollie returns and learns that Giles is taking Trotter on a tour. Metcalf reveals that Mrs. Boyle was involved with the case, as a magistrate who sent the children to Longridge Farm. Mollie seems to recognize her, and Paravicini leaves the room laughing.

Mollie and Miss Casewell share suspicions about Paravicini, Metcalf leaves to get wood for the fire, and Mrs. Boyle goes to the library. Paravicini picks out “Three Blind Mice” on a piano offstage. Mollie and Miss Casewell talk about memory and moving on from the past (this foreshadows that Miss Casewell has overcome the trauma of her childhood at Longridge Farm while her brother has not).

Giles and Trotter return. Miss Casewell goes offstage to the dining room after Trotter has inspected it. He inspects the drawing room, offstage, then says he wants to call in a report to his superintendent. When Mollie tells him the phone is dead, Trotter suspects the line has been cut (the irony here is that he cut the line). He questions Giles and Mollie about the guests, hinting that one of them is the murderer; the couple admits they don’t know much about them.

Mollie heads to the kitchen to cook, and Giles—at Trotter’s request—goes to check the upstairs phone extension. On his way out, Giles notices a London bus ticket in Mollie’s glove (it turns out she was buying him an anniversary present, but he becomes suspicious). Trotter follows the phone wire out of the window.

Mrs. Boyle comes in and closes the window. She turns on the radio, and someone starts whistling “Three Blind Mice” offstage. A hand reaches into the room and turns out the lights. In the darkness, Mrs. Boyle’s the audience can hear Mrs. Boyle being murdered. Mollie reenters the room, turns on the light, and discovers the body. As she screams, the curtain falls for the end of Act I.