The play opened in London's West End in 1952 and ran continuously until 16 March 2020, when the stage performances had to be temporarily discontinued during the COVID-19 pandemic.

[2] Richard Attenborough was the original Detective Sergeant Trotter, and his wife, Sheila Sim, the first Mollie Ralston – owner of Monkswell Manor guesthouse.

[4] The story drew from the real-life case of Dennis O'Neill, who died after he and his brother Terence suffered extreme abuse while in the foster care of a Shropshire farmer and his wife in 1945.

Tom Stoppard's 1968 play The Real Inspector Hound parodies many elements of The Mousetrap, including the surprise ending.

"[16] When it broke the record for the longest run of a play in the West End in September 1957, Christie received a mildly grudging telegram from fellow playwright Noël Coward: "Much as it pains me I really must congratulate you ..." In 2011 (by which time The Mousetrap had been running for almost 59 years), this long-lost document was found by a Cotswold furniture maker who was renovating a bureau purchased by a client from the Christie estate.

[19] The original West End cast included Richard Attenborough as Detective Sergeant Trotter and his wife Sheila Sim as Mollie Ralston.

[2] They took a 10% profit-participation in the production, which was paid for out of their combined weekly salary ("It proved to be the wisest business decision I've ever made ... but foolishly I sold some of my share to open a short-lived Mayfair restaurant called 'The Little Elephant' and later still, disposed of the remainder in order to keep Gandhi afloat.

The change usually occurs around late November around the anniversary of the play's opening, and was the initiative of Sir Peter Saunders, the original producer.

The late Deryck Guyler can still be heard, via a recording, reading the radio news bulletin in the play to this present day.

The set was changed in 1965 and 1999, but one prop survives from the original opening – the clock which sits on the mantelpiece of the fireplace in the main hall.

[26] During the diamond anniversary year of The Mousetrap, a touring production visited regional theatres for the first time in its history, whilst the London run continued uninterrupted.

[35][36] Duncan Leatherdale of BBC News contrasted the play to other works like Psycho and The Sixth Sense, where the plot twist has been revealed and became itself an element of popular culture.

The action then moves to Monkswell Manor, recently converted to a guesthouse and run by a young couple, Mollie and Giles Ralston.

While waiting for the guests to arrive, Mollie listens to a radio report about the Lyon murder, which notes that police are looking for a man in a dark overcoat, observed near the scene.

In a story loosely based on the real Dennis O'Neill case, the dead woman and her husband had mistreated their three foster children, resulting in the death of the youngest.

Both adults were imprisoned for their actions; the husband died in gaol, while the wife served her sentence and had been released, only to be found strangled.

Trotter reveals that a notebook found at the murder scene contained the address of Monkswell Manor and the words "Three Blind Mice".

While Trotter and Giles tour the house, Major Metcalf confronts Mrs Boyle, revealing that she was one of the magistrates who had assigned the children to the foster parents.

The opening notes of "Three Blind Mice" are heard whistled by an unknown party and Mrs Boyle responds without alarm, speaking to the person only she can see.

Ten minutes after Mollie finds Mrs Boyle dead of strangulation, Sergeant Trotter takes charge of the household.

Frustrated, Trotter points out that their lives continue to be in danger; a third murder could very well happen, given the notes left with Maureen Lyon.

Giles counters that while seven people in the house lack alibis, only one fits the description of the man the police suspect to be the murderer: Christopher Wren.

Mollie soon finds herself in conversation with Christopher Wren, who confesses that he is actually an army deserter hiding from his past under a false name.

Trotter takes a gun out of his pocket and points it at Mollie, telling her that she had only assumed him to be a policeman based on the telephone call.

Falling back into the demeanour of a wounded child who never grew up, he drops his gun and begins to strangle Mollie, but is stopped by the sudden appearance of Miss Casewell.

[40] The reviewer in The Times was more favourably disposed to the characters, calling them "nicely assorted, individually labelled and readily identified", and found the plot "elaborately skilful.

"[41] In The Daily Express, John Barber praised "the atmosphere of shuddering suspense" but thought some of the characters "too obvious by half".

[42] In The Illustrated London News, J. C. Trewin commented that those who failed to spot the killer would probably call the plot "preposterous and over-burdened", but those who succeeded might be more kindly disposed.

In 1959, it was announced that Edward Small, who had produced Witness for the Prosecution for the screen, was to make a film version of the play in co-production with Victor Saville for United Artists.

[47] In 2022, the story of a British-American film See How They Run was set in the Ambassadors Theatre and concerned in-story actors of The Mousetrap, following murders of personnel involved in the production of and linked to the play.