A 1952 play by Creator/AgathaChristie adapted from her 1947 radio play, "Three Blind Mice". Since its opening night in London Soho, the play has been running ''continuously''. It holds the world record for longest running show (of ''any'' type) of the modern era.

The plot takes place in a guest house called Monkswell Manor, run by a Mr. and Mrs. Ralston. They've only just inherited the house, close to where Mrs. Ralston grew up, and they're excited about the arrival of their very first guests. On their first night running the guest house, however, the Ralstons and their four odd lodgers are snowed in during a blizzard. The radio announces that a serial killer is on the loose -- one who uses the children's song "Three Blind Mice" as a {{Leitmotif}}. And the more and more time passes, the more and more reason there is to believe that the killer may be inside Monkswell Manor. When one of the guests indeed ends up murdered, suspicion starts falling on anyone and everyone in the manor. Suffice to say, there are a ton of twists which unfold slowly over the entire course of the tale.

[[DoNotSpoilThisEnding And that's all we're going to say.]] Sorry!
!!This work features examples of:
* AmbiguouslyGay: Many viewers think that Christopher Wren is supposed to be gay, based on his mannerisms and finding Sgt. Trotter to be attractive (as a policeman), "terribly hearty", etc. Officially, he's not.
* AssholeVictim: [[spoiler:Mrs. Boyle]] is such a snobbish, callous, unlikeable character that few theatregoers shed tears at [[spoiler:her]] death at the end of the first act.
* TheAtoner: Several characters are trying to escape their past, and one feels sorry about something that they had done.
%%* BluffingTheMurderer
* TheButlerDidIt: A theatreland joke tells of a cab driver who, dropping his passengers off outside the theatre showing ''The Mousetrap'' and, feeling angry about not getting a tip, yells "The butler did it!" and drives off. [[DontExplainTheJoke The joke relies on you knowing that]] [[AvertedTrope there isn't a butler in the play.]]
* ChekhovsGun: The box Giles puts in the window seat and the package Mollie puts in the desk drawer at the beginning of the show.
* ClosedCircle: By snowstorm and cut phone lines.
%%* ConvictionByContradiction: Deconstructed [[spoiler:and arguably outright denied]].
* CutPhoneLines: Done by the murderer to further isolate the guesthouse from the outside world.
* DoNotSpoilThisEnding: At the end of the play, the audience is asked not to spoil the ending. No film adaptation (or any other adaptation, for that matter) is allowed to be made while the play is still running. Mass market publication of the script is not allowed in the United Kingdom either. Since it's been running for ''sixty years'', it's likely no adaptation will ever see the light of day. As a matter of fact, Wiki/TVTropes ain't spoiling either. Got that?
** There's a much nastier variation of the joke from TheButlerDidIt above; in it, the cab driver has actually ''seen'' the play, and he yells out the name of the actual culprit while driving off.
** The USSR didn't particularly care about those nasty capitalist rules, and, therefore, produced in 1990 a pretty straightforward movie adaptation.
** Wikipedia, naturally, notes the ending on its page about the play, much to the dismay of the present owner of the play.
** ''Three Blind Mice'' was eventually released as a book, but its foreword proudly announced that it had been banned for decades.
* EveryoneIsASuspect: There is a reason why the tagline for the play in the brochures is, "Suspect Everyone". The only person not played up at possibly being the murder is Mollie.
* FauxShadow: Virtually every character gets it at some point, always done very well.
* {{Foreshadowing}}: While there are many {{Red Herring}}s scattered throughout the play, there are some genuine hints as to the killer's identity as well; one character's reaction in particular to the announcement that the Berkshire Police are sending Sgt. Trotter to the house foreshadows some of the biggest twists in the play's denouement.
* FosteringForProfit: It is mentioned that PosthumousCharacter Maureen Lyon and her husband had used their three foster children as essentially slave labour on their farm, with their ill-treatment resulting in the death of one of the children.
* FunnyForeigner: Mr. Paravicini is generally played with a comically over the top Italian accent and mannerisms, contributing to a sense that he may not be all he claims to be.
* HateSink: Mrs. Boyle serves this purpose - she is a universally unliked, unpleasable elitist old nagger.
* {{Jerkass}}: Mrs. Boyle can get pretty mean at times, questioning Mollie's motives at running a guest house and not showing a speck of remorse for the death of the Corrigan boy. [[spoiler: It's no wonder she gets killed at the end of act one]].
%%* TheLadette: Miss Casewell.
* LongRunner: It has run since its opening, and is in fact the longest running theatrical production ''period.''
* MetaGuy: Paravicini frequently names conventions of the "cosy" crime fiction genre, proving to be quite GenreSavvy. These include highlighting the dangers of not knowing the guests, commenting on the convenience of the isolation of the characters, and asking Trotter not to spoil the "ending" (reveal the murderer), as the last scene/reveal is always the best scene.
* MinimalistCast: Due to the entire play taking place in ''a single room'' in the middle of a snowstorm. There are just eight characters: Giles and Mollie Ralston, Christopher Wren, Major Metcalf, Mrs. Boyle, Miss Casewell, Mr. Paravicini, and Sgt. Trotter.
* OldDarkHouse: The play is set in Monkswell Manor, a sprawling manor house converted into a guesthouse.
* PlotTriggeringDeath: The events of the play are set in motion by the murder of Maureen Lyon, whose abuse of the three Corrigan siblings, to whom she and her husband were foster parents, led to the death of one of them. Several characters in the play, including the killer, are revealed to be connected to the Corrigan case.
* PosthumousCharacter: Maureen Lyon, whose murder is heard (but not seen) at the start of the play.
* RedHerring: Take a shot every time there's one of these and you'll be unconscious by the end of the first act.
* RunningGag: Early in the play, when a new character arrives at the house, the description of the killer's clothes is given, usually as they take each item off.
* SnowedIn: During the entire play.
* SplitPersonality: It is hinted the killer may have a split personality as a result of a traumatic past experience. The personality of the killer is the one who underwent the trauma, while the personality they display in their cover identity was developed as a defence against said trauma.
* SurprisinglySuddenDeath: The killer manages to strangle [[spoiler: Mrs. Boyle]] to death in about five seconds.
* SuspectIsHatless: The radio description of the killer is actually pretty good, except for the fact that it could potentially describe ''every single character in the play''.
* TenLittleMurderVictims: What the characters trapped in the house suspect is going on, although it's theorized that there will only be three.
* ThisIsReality: How the other characters react to Paravicini commenting on the action unfolding around them as if it was a mystery story.
%%* UpperClassTwit: Christopher Wren.
* WhoMurderedTheAsshole: Maureen Lyon, the first 'blind mouse'/murder victim, was an [[AbusiveParents abusive foster mother]] to the three Corrigan children, causing the death of the youngest. The second blind mouse was [[spoiler: Mrs. Boyle, whose HateSink and Jerkass trope entries speak for themselves. She was also the person who placed the Corrigan children with the Lyons, and shows no remorse about their fate]]. It's theorized that the murderer is one of the children that Maureen abused, getting revenge on people involved in the tragedy (Maureen's husband isn't targeted because he died in prison), or one of the Corrigans' loved ones going after them for the same reason.
* WhamLine: Although in the interest of maintaining the spoiler policy, the context and speaker are omitted.
--> The police don't.
* WhatHappenedToTheMouse: Most of the loose ends are tied up by the end of the play, but a few characters are left with their background unexplained.
By the way, the murderer is...[[spoiler:not to be revealed on this wiki.]]