Locked Room Mystery - Television Tropes & Idioms

alt title(s): Locked Room

A seemingly impossible crime. The standard example being that of a murder victim found in a room with only a single door, securely locked from the inside. Can be the basis for a single plot, or an entire show. A well-designed Locked Room Mystery provides pleasure from trying to figure out the puzzle before it is revealed, from moments of dawning realisation, and from a satisfyingly logical solution. A poorly designed Locked Room Mystery only provides a feeling of having been cheated.

Originally from crime fiction, John Dickson Carr being an acknowledged master. It is noteworthy that Edgar Allan Poe's short story The Murders in the Rue Morgue, widely considered to be the first detective story, involves a Locked Room Mystery.

Appears on television in a number of forms. The relatively pure form as a sub-genre of crime television (e.g., Monk, Jonathan Creek) where the puzzle is eventually unravelled by an eccentric protagonist using subtle clues and pure reason.

The part of the show where the solution to the mystery is explained is The Summation. Common causes include Time Delayed Death or a Wounded Gazelle Gambit.

Examples:

Anime and Manga

Although it is not a crime show, the anime Spiral has a number of locked room mysteries that the protagonist must solve, including one literal locked room murder.
The Suzumiya Haruhi two part episode "Remote Island Syndrome" (and the corresponding chapter in one of the light novels) has a fairly brilliantly-executed example of this.
Detective Conan frequently uses these. Mostly, the killer sets up an elaborate trap involving string or melting ice.
- Similarly, The Kindaichi Case Files features one almost every story.
The "game" between Battler and Beatrice consists entirely of these in Umineko No Naku Koro Ni.
One of these came up very recently in Kuroshitsuji.

Comic Books

Donald Duck and especially Mickey Mouse comics occasionally feature rather lame versions, most commonly involving the Phantom Blot, the evil mastermind opposed to Mickey conceived as an amateur or even professional detective. If it seems the crime could only have been committed by a thief who could turn invisible or whatever, that's probably exactly what he did with the help of some gadget. Oh, and there exist a few decent stories as well that actually feature a real mystery of this sort.
A staple of The Maze Agency comic book series.

Film

To some extent, I, Robot fits this trope: Dr. Alfred J. Lanning's death looks like an open-and-shut suicide because the door to his room was locked. Spooner, of course, thinks otherwise.
Lampooned in the movie Murder by Death, which pretty much makes fun of all fiction crime characters - Sidney Wang modeled after Charlie Chan, Sam Diamond modeled after Sam Spade - and their methods of baffling their readers.

Literature

The original locked room mystery is The Murders in the Rue Morgue, by Edgar Allan Poe. The story became the Trope Codifier for later detective murder mysteries.
The most famous Sherlock Holmes locked room mystery is probably The Case Of The Speckled Band.
Parodied in the Discworld short story Theatre of Cruelty, in which Vimes's Internal Monologue brings up the complaint that "wizards made locked room mysteries commonplace" (though there are never any actual examples of this happening in the series).
- Unless you count the poisoning of Lord Vetinari in Feet of Clay, which is a completely fair locked room mystery. He got better.
Happens in the Finnegan Zwake series with the man in Finn and Stoppard's storage room (in Horizontal Man) and Professor Freaze in his tent (in Worm Tunnel).
Intentionally played to the point of absurdity in the second Dirk Gently novel by Douglas Adams, The Long Dark Tea Time of the Soul. Dirk finds that his newest client, a wealthy man who had hired him as a security guard, had his head severed and placed on an active record machine while awaiting Dirk. Of course, the door to the room was locked from the inside when the scene was initially discovered. The police analyze this as an elaborate suicide done simply to cause trouble.
Occurs in Jeffrey Deaver's novel The Vanished Man, where the killer is seemingly able to escape from a locked room where one of his victims is found, as well as disappear into a small crowd.
Played with in Jasper Fforde's The Big Over Easy, a detective story using nursery rhyme characters. "The entire crime-fighting fraternity yesterday bade a tearful farewell to the last 'locked room' mystery at a large banquet held in its honor. The much-loved conceptual chestnut of mystery fiction for over a century had been unwell for many years and was finally discovered dead at 3:15 A.M. last Tuesday."
- Then it turns out that the locked room mystery was murdered...in a locked room.
In her non-fiction book Sex Crimes, Alice Vachss (wife of crime writer Andrew Vachss) mentions a real life case that she prosecuted, where the accused was locked in his room every night by nuns, and so supposedly could not have commited the rape. In the end the jury decided that any youth in that position would have found a way out of his room long ago.
John Dickson Carr, the acknowledged master of this back in the golden age of crime fiction, provided all sorts of different ways to accomplish this. In his book The Hollow Man/The Three Coffins, the main character actually gives a lecture on the different ways a locked room mystery can be created.
- All John Dickson Carr and Carter Dickson (his obvious pseudonym) mysteries featuring either Dr. Gideon Fell, Sir Henry Merrivale, or the French detective Bencolin are going to be 'locked room mysteries', even there is not a lock, or even a room.
Randall Garrett used this trope often in his Lord Darcy stories, with the added twist that magic is real in Darcy's world. Magicians naturally become prime suspects in a Locked Room Mystery, yet Lord Darcy often works out a non-magical explanation, thus exonerating some innocent wizard of the crime.
Death in the Dawntime, by F. Gwynplaine Macintyre was written specially for The Mammoth Book Of Historical Detectives, and probably has the earliest setting ever for a detective story. It's a Sealed Cave mystery.
- The Mammoth Book of Historical Whodunnits opened with the Ancient Egypt-set The Locked Tomb Mystery by Elizabeth Peters, which is Exactly What It Says On The Tin.
Stieg Larsson's Men Who Hate Women is about a journalist investigating a forty year old murder mystery which is a Locked Room Mystery on an island.
Ellery Queen had a number of locked room mysteries, including The Chinese Orange Mystery.
The Psych tie-in novel "Mind over Magic" centers on the case of a costumed magician who appears to dissolve into nothingness in a water tank before a crowd of spectators but never reappears after the illusion, with a dead body suddenly in the tank in the magician's place.

Tabletopgames

In warhammer fantasy battles Deathmaster Snitch killed an imperial noble that had locked himself into a tower with the only door being guarded by a large band of knights. The knights didn't notice anything until the following morning. Bonus point as no explanation is given for how he did it, making it even more of a mystery (you can't flip to the last pages and learn what happened).

Live Action TV

A more diluted form sometimes appears in a Police Procedural (e.g., CSI) where the puzzle is eventually unravelled by an eccentric protagonist using more obvious clues and Applied Phlebotinum.
In genre television (e.g., The X Files), the puzzle is typically subverted when an eccentric protagonist (Agent Mulder), on the basis of flimsy evidence and wild speculation, reveals that a Monster Of The Week did it. In this case the Monster Of The Week is the one using Applied Phlebotinum in the form of special monster powers.
Jonathan Creek is a show built around various locked room mysteries and other seemingly impossible crimes and events, such as a woman being seen going to church in her hometown while she was supposed to be in a coma, a murder seemingly being committed by someone who was already dead and a man being witnessed in both Britain and America simultaneously.
Monk doesn't usually have crimes that look totally impossible, just ones that look impossible for Monk's prime suspect to have committed. The prime suspect is always guilty anyway. Some episodes turned this Up To Eleven, with one killer who was in outer space at the time of the murder, and still turned out to be guilty, and another where a guy managed to commit murder while in a coma.
One Crossing Jordan episode involved a man who was writing a book on vampires found dead in a locked room, drained of blood and with fang wounds in his neck. It turned out to be self-inflicted.

Video Games

The second Ace Attorney has a case where your assistant is locked in an empty room with the victim, a gunshot is heard, and the door is opened to reveal her standing over the corpse with a smoking gun in her hand. Naturally, it now falls on you to prove her innocent in court.
- Another case involves a man found dead in the middle of a snow-covered courtyard with only one set of footprints leading to the body... and an eyewitness who saw the killer leave the murder scene by flying over the rooftops.
  - By the way, John Dickson Carr (see above) invented this style of locked room mystery too.
An interesting inversion of this trope occurs in Elder Scrolls IV: Oblivion during a side mission; You and five other people are locked into a mansion on the premise that hidden somewhere in the house is a chest full of gold. Whoever finds it gets to keep it. A fun little game between friends, right? But soon, people start turning up dead, one by one, and suspicions fly as to who the killer is. Now, here's the twist; This is a Dark Brotherhood, a.k.a. Assassin's mission. YOU are the killer. The other five people are all targets, the mission is to kill them without them knowing you are the killer, and just for giggles, you're holding the only key to the front door.
- Oh, yeah, and there's no gold, either. Well, not for them, anyway.
- Unfortunately, it's programmed so badly that they never notice that you're the murder even if you do it in front of them.
Invoked repeatedly in Umineko No Naku Koro Ni, where it forms the core of the argument that the culprit must be the Golden Witch Beatrice instead of a human. Beatrice is knowledgeable about the classics and goes to some lengths to rule out the obvious solutions.
- Bonus points to the first twilight of the third arc; six people are found murdered in six different locked rooms, and each one has the key to one of the other rooms on their corpse.