The Mousetrap

Set in Berkshire, England, around 1950, the play opens with a voice on the radio reporting the recent murder of a woman named Maureen Lyon, who was strangled to death on Culver Street in London. According to the police, the suspect of the crime was wearing an overcoat, scarf, and felt hat. Additionally, the radio announcer warns of a winter storm that will bring heavy snowfall throughout the evening.

Mollie Ralston and her husband, Giles, return from their separate errands to Monkswell Manor, an old house Mollie has inherited from her aunt and that the couple has decided to run as a guesthouse. While Mollie turns off the radio, Giles takes off his overcoat, scarf, and hat and warms up by the fireplace. Then, their four guests arrive one by one. The first is a peculiar, childish young man called Christopher Wren, whom Giles immediately dislikes. The second is an old, irritable woman named Mrs. Boyle, who complains about the cold weather and lack of proper amenities at the manor. The third is Major Metcalf, a middle-aged military man. And the fourth is Miss Casewell, a young woman with a brusque manner. As these guests all settle into the rooms they have rented, the doorbell rings again unexpectedly. Giles answers the front door to discover an elderly foreign man who introduces himself as Mr. Paravicini. He says his car overturned in a snowdrift nearby and asks for a room at the manor. Mollie agrees to let him stay. Inside, Mr. Paravicini declares that the blizzard will soon cut the house off completely from the outside world—no one will be able to enter or leave.

By the next afternoon, Monkswell Manor is snowed in. While Mrs. Boyle quibbles with the other guests, Mollie receives a phone call from the Berkshire Police. She learns that a sergeant is being sent to the manor. A little later, Detective Sergeant Trotter shows up, having reached the house on skis. Sergeant Trotter explains to everyone that at the scene of Maureen Lyon’s murder, the police found a notebook containing the addresses for both Culver Street and Monkswell Manor. So, Trotter’s duty is to determine who at the manor has connections to Maureen Lyon—the killer’s first target—and to protect the manor’s residents from becoming the next murder victims. Crucially, Trotter suspects there may be more killings because the murderer also wrote “Three Blind Mice” in the notebook at the crime scene, implying that there will be three total victims.

Furthermore, Trotter explains that Maureen Lyon’s real name was Maureen Stanning. Years ago, she and her husband, John, were found guilty in the infamous Longridge Farm case, in which they severely mistreated and neglected three foster children. After the youngest child, Jimmy Corrigan, died, the Stannings were arrested and imprisoned. The police suspect that the eldest Corrigan child killed Maureen Stanning in revenge for the cruel abuse he and his siblings suffered. Now, Trotter asks everyone at Monkswell Manor if they had any involvement in the Longridge Farm case. Nobody offers any information, so Trotter searches the house.

While Trotter is occupied, Major Metcalf confronts Mrs. Boyle. He recognizes her as one of the magistrates who sent the Corrigan children to live with the Stannings at Longridge Farm. Mrs. Boyle admits that Metcalf is right, but she denies any responsibility for what happened to the children. In the meantime, Trotter tries to call the police station and realizes that the telephone is dead. He believes that someone has deliberately cut the phone line. As he leaves to check the telephone wire outside, Mrs. Boyle sits in the entrance hall alone. Suddenly, she hears someone whistling “Three Blind Mice.” All the lights shut off, Mrs. Boyle struggles, and then she collapses, dead. Mollie finds her body and screams.

Trotter questions Mollie if she heard or saw anything that could identify Mrs. Boyle’s murderer, but Mollie is too distressed to remember. Next, Trotter summons everyone to the entrance hall and interrogates them as to their whereabouts at the moment of Mrs. Boyle’s death. Each person claims to have been in a different room, so no one’s location can be corroborated. As a result, Trotter concludes that everyone is a suspect. Angrily, Giles accuses Christopher as the only likely killer, but Mollie refutes this. In a private conversation between Mollie and Trotter, the sergeant raises the possibility that Giles could have killed both Mrs. Stanning and Mrs. Boyle. As evidence, he shows Mollie a newspaper Giles hid in his overcoat pocket. The newspaper proves Giles was in London on the night of Mrs. Stanning’s murder. Mollie is horrified that her own husband could be lying to her. She confronts Giles about the newspaper, and in retaliation he shows her a bus ticket to London that he found tucked inside one of her gloves. Mollie herself has traveled to London secretly, and she refuses to explain why.

Trotter devises a plan to catch the murderer. He sends everyone away to different rooms and then calls Mollie into the entrance hall. Alone with her, he pulls out a gun and reveals that he’s Georgie Corrigan. He wants to kill Mollie, who used to teach at the school he and his siblings attended, because he blames her for not helping them. His younger brother, Jimmy, wrote her a letter begging her for help—but Mollie, who was ill at the time, didn’t read the letter until it was too late. Before Georgie can harm Mollie, Miss Casewell emerges and reveals herself to be his younger sister, Kathy Corrigan. She persuades Georgie to come with her someplace where he’ll be cared for. Then Major Metcalf, who is actually an undercover policeman, sedates Georgie. Safely reunited, Mollie and Giles learn that they each went to London to buy one-year wedding anniversary gifts for each other. They exchange presents and happily reconcile.