->"Literature/HerculePoirot just got off the steamy train. If you want my opinion, I think they all did it."
-->-- '''Holly''', reading ''Literature/MurderOnTheOrientExpress'', ''Series/RedDwarf''

A famous detective has [[SummationGathering gathered a group of likely suspects.]] They analyze the evidence, interview the suspects, and thoroughly investigate the crime scene in order to figure out which of the gathered people is the culprit. The conclusion? Everybody was. As opposed to having one or two people commit a crime out of several potential suspects, ''all'' the suspects were in on it to some extent.

Not related to the other kind of "doing it." [[EverybodyHasLotsOfSex Usually]].

'''MAJOR spoilers in the below examples obviously'''.

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!!Examples:

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[[folder:Anime and Manga]]
* A filler episode of the ''RanmaOneHalf'' anime had an investigation of "who stole the takoyaki?" complete with Shout Out to a famous samurai mystery drama series (famous in Japan, that is...)
* Chapter 30 of ''FrankenFran'' is set up as a typical murder mystery, and sure enough, people start getting attacked, although Fran manages to keep them alive. [[spoiler:It turns out that they're injuring themselves, because they enjoy having Fran operate on them.]]
* Seems to be part of the point that the various narrators are trying to make in UminekoNoNakuKoroNi. [[spoiler:Any time the parents find the gold, they will inevitably begin offing one another like crazy in a bid to [[GoldFever keep it for themselves]], making every single one of them possible culprits]].
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[[folder:Comicbooks]]
* Peter Milligan's ''ShadeTheChangingMan'' used this to ''avoid'' solving the mystery of "Who Shot JFK?", instead Hand Waving with a glancing look at every possible speculation, then concluding that EverybodyDidIt. Justified in that Shade is a stranger to American culture, and that he was dealing with a madman's obsession covering up for grieving his lost daughter.
* In the ''{{Franchise/Batman}}'' storyline ''ComicBook/TheLongHalloween'', Batman is looking for a serial killer targeting mobsters. All three of the suspects end up having done at least some of the murders, though none of them knew who the other killers were.
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[[folder:Films]]
* The murders committed in ''Film/HotFuzz'' were pulled off by the NWA (Neighbourhood Watch Alliance), which consisted of almost every named character in town.
* PlayedForLaughs in the climax of ''ThePinkPanther'' movie ''AShotInTheDark''. Clouseau's interrogation goes completely out of control as the different suspects start bickering amongst each other and shouting accusations; from this, he is somehow able to deduce that "they were all murderers, except for Maurice, who was a blackmailer!"
* This is how ''[[TheBlairWitchProject Blair Witch 2: Book of Shadows]]'' ends... maybe...
* Inverted- In the 1955 [[Creator/AlfredHitchcock Hitchcock]] film ''TheTroubleWithHarry'', a town of people find the body of a dead resident, Harry. Everyone believes themselves and everyone else to be responsible for the death. It turns out that no one did it, and Harry died of natural causes.
* The third ending of ''Film/{{Clue}}''. All but one of the surviving characters end up having killed someone, as does one of the victims. And it even [[ItMakesSenseInContext makes sense in context]].
* Half the town tried to kill the eponymous character in DrowningMona, though most of them were pretty incompetent about it.
* ''GosfordPark'': [[spoiler:the AssholeVictim was the father of the would-be murderer by his housekeeper, who knew her son was planning to kill him and got there first so that he'd be guilty only of stabbing a dead body]].
* The film version of ''Murder on the Orient Express'' is an even better example of this than the book.
* This turns out to be the reason Owen believed there actually was a killer in ''Film/CryWolf'': It was a combination of an elaborate hoax and a pile of coincidences that more or less involved everyone around him playing pranks. [[spoiler:Then you find out Dodger's one ''hell'' of a [[TheChessmaster Chessmaster]] and set the whole thing up to get away with killing Mr. Walker.]]

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[[folder:Literature]]
* The former TropeNamer would be the Creator/AgathaChristie novel ''MurderOnTheOrientExpress'', where [[EveryoneIsASuspect everyone was suspected]], and for good reason. [[ItWasHisSled Not really a spoiler any more.]] Also the TropeMaker and UrExample.
** This is actually a rather more thoroughly analyzed version than you might think at first glance. Everyone on the train except the victim and the detectives was part of an elaborate conspiracy to execute the victim. The original idea was to provide themselves with an interlocking net of alibis, such that guilt could never settle on any of them and it would be assumed that someone from outside the train did it. If it hadn't been for a ClosedCircle snowdrift cutting of the hypothetical murderer's escape, it might have worked.
* Subverted in the Randall Garrett ''Literature/LordDarcy'' story, ''The Napoli Express'' (whose name is an obvious shout-out to the Christie novel). When the non-hero detective comes up with the "they all did it" theory, the hero has to restrain himself from saying how silly the idea is. The people involved can't even hide that they all know each other, even though they're trying to. Hiding that they conspired together to commit the murder is quite ridiculous.
** The whole story is a ShoutOut to the Christie original. Garrett's solution even harks back to the one Poirot presents as the alternative to the trope.
* Reginald Hill's ''Literature/DalzielAndPascoe'' series parodies this trope in ''Pictures of Perfection.'' Virtually every major character commits ''some'' sort of crime, [[spoiler:except for murder.]] Much to Dalziel's irritation, [[spoiler:nobody wants to file charges against anybody else.]]
* OlderThanPrint: ''TheTroubleWithHarry'' is based on "The Tale of the Hunchback" from ''The ArabianNights''.
* ''[[Literature/SmallChange Farthing]]'' by Creator/JoWalton is set up to appear like a classic [[GenteelInterbellumSetting interbellum]] country-house murder mystery. It's not. It's a political conspiracy. The "Farthing Set", a group of fascisticly-inclined young upper-class political risers, arrange to kill one of their own members, James Thirkie. As a result, Mark Normanby becomes Prime Minister on a wave of sympathy; and the framing of an English Jew and an Irishman alleged to be an anarchist helps complete the country's slide into fascism. Other members of the Farthing Set also wind up well-placed in the new government. Widowed Angela Thirkie also benefits and takes off with the chauffeur. Anyone who knows anything disproving the conspiracy is KilledToUpholdTheMasquerade, including Thirkie's own mother.
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[[folder:Live-Action TV]]
* ''Series/ThirtyRock'' episode ''It's Never Too Late For Now'' is a WholePlotReference to ''MurderOnTheOrientExpress'' - Liz is even watching the 1974 film. The "crime" is that there was a conspiracy to get her laid with a Canadian gigolo. Like Poirot, she rejects the complex (though true) answer that all of her co-workers felt bad for her and got her laid, but the simple explanation that she met a guy, and had fun night.
* ''Series/VeronicaMars'': a late season 1 episode reveals that [[spoiler:basically all the 09'ers were complicit in Veronica's rape, including her future boyfriend Logan, who supplied the drugs for the party]].
* Comically subverted in the British spoof anthology series ''MurderMostHorrid'' starring DawnFrench: in the episode "The Case of the Missing", everyone ''did'' do it, but the detective assigned to the case (French) is so confused and frustrated by their manipulation of the evidence that she finally snaps and concludes that she must have done it.
** Subverted again in the episode "Mangez Merveillac". Obnoxious travel writer Verity Hodge (French again) makes the French town of Merveillac a hugely popular tourist destination by forcing the locals to conform to stereotypes. Eventually, the locals grow tired of this, murder Hodge, and serve her up to the tourists at a local festival. [[spoiler:However, once the credits roll, we discover that Hodge is actually alive and well, and the "murder" was part of a scheme to draw even more tourists to Merveillac by inspiring a Hollywood blockbuster.]]
* In ''TheLWord'', at the end, Cathy could have been killed by anyone.
* In ''Series/StarTrekDeepSpaceNine'', this is basically how Cardassian mystery novels are said to play out, with all the suspects being guilty; the mystery is figuring out who is guilty of what.
* The episode of ''Series/{{Monk}}'' where he went to a vineyard. He meets a guy, but the next day, everybody denies that he existed. [[spoiler:The guy stole money from his employers and died of a heart attack. The other guests find out and agree to split the money, but hid the truth from Monk because he's honest, so they erase all traces of the man's existence]].
** Another case involve a bank robbery [[spoiler:in which the entire robbery was staged by all of the staff in bank.]]
* This was used in an episode of ''Series/ColdCase''--specifically, [[spoiler:the one about the virginity club. The victim knew something incriminating about each other member of the club, so they decided to kill her together. By stoning, no less]]. (Yes, it was a touch {{Anvilicious}}.)
* One tongue-in-cheek episode of ''Series/{{CSI}}'' concerned a man found dead in a swimming pool. Every time Doc Robbins finds a possible cause of death, it looks like a new suspect is to blame for his injuries, whether for intentional homicide or reckless endangerment. Eventually it turns out that the repeatedly-battered man sat down to recuperate, slipped into the pool when his deck chair collapsed, [[SubvertedTrope and accidentally drowned]], meaning Everybody ''Failed'' To Do It.
** And played straight in "[[DeathInTheClouds Unfriendly Skies]]", when mob rule took over and they all had a hand in killing the guy.
** Also played straight in "Rashomama" in that all the bridesmaids had a hand in the death of the mother of the groom.
* The ''JonathanCreek'' episode "Satan's Chimney", wherein the second murder victim was killed for inciting the murder of the first victim, by the first victim's friends.
* PlayedForLaughs in the ''RippingYarns'' episode "Murder at Moorstones Manor," which ends with a standoff between the characters claiming credit for the murder.
* In an episode of ''FoylesWar'', the victim is hit over the head with a rock and then drowned in a trough. It turns out these assaults were committed by two different people, and witnessed by a third would-be assailant who never got his chance to do anything. The rock-wielder is let off, with {{lampshading}} to the effect that he's just lucky half the town was out to get the guy that night.
* ''SaturdayNightLive'' once had a "[[Series/{{Dallas}} Who Shot J.R.]]" parody in which everyone shoots a Texan {{Jerkass}}, then discover one person did ''not'' have live ammo, and they try to figure out who ''didn't'' shoot him.
* ''Series/ElleryQueen'': Not ''everybody'', but in "The Adventure of [[spoiler:the Comic Book Crusader]]", three of the five suspects end up being guilty of the murder.
* In ''Series/TheMentalist'' episode "Red Tide", the CBI investigates a group of teenagers to see who among them killed a mutual friend of theirs. Through their investigation, it is eventually [[TheReveal revealed]] by Jane that since everyone liked to pass the blame, they all committed the crime.
* ''MajorCrimes'': In "There's No Place Like Home", all of the tenants are responsible for the death of the landlord. As Major Crimes can prove conspiracy to commit murder, but not if the death was actually murder, the killers cop to a collective plea of manslaughter.
* On ''Series/{{Dallas}}'' One of the major plot twists was the someone shot and killed Main Character J.R. . To avoid any leaks the producers, cast, and crew shot scenes of everyone's character individually shooting J.R..... [[UpToEleven Up to and including J.R. himself ambushing himself in his own office and mercilessly gunning himself down.]]
* In the ''Series/LawAndOrderSVU'' arc in which Captain Cragen is accused of murder ("Rhodium Nights" to "Above Suspicion"), it turns out every single guest character in the episodes is involved in the murders in some way, including both of the defendants' attorneys, a rookie cop who initially seemed to just be in the wrong place at the wrong time, [[spoiler: and even the prosecutor, who had been bribed by one of the suspects with money for her disabled daughter]].
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[[folder:Music]]
* The [[http://www.youtube.com/watch?v=M7byjAaLcRM&feature=channel video]] for ''Who Spiked the Eggnog?'' by the group Straight No Chaser had the lead singer as an UnreliableNarrator, and tried to finger his fellow singers as the guilty parties. We see them around the eggnog in question, and a few of them DO seem to perform the deed. [[spoiler: The last scene of the video shows the lead singer guilty of the act as well.]]
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[[folder:Theater]]
* The JB Priestley play ''AnInspectorCalls'' features this trope to a degree. Although the girl committed suicide, the entire Birling family drove her to it one way or another, and this drives the acceptance of social guilt that Priestley wrote the play to emphasize.
* When the YMCA or similar organizations hosts a murder mystery game for kids, they'll use this solution. What's more, there will be evidence pointing to everyone. Presumably, this is so no matter what you guess (unless you guessed [[WhatAnIdiot suicide]]), you're never completely wrong, and all the kids go home feeling more or less satisfied.
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[[folder:Video Games]]
* In ''AceAttorneyInvestigations'', [[spoiler:Callisto Yew]] claims to be the [[PhantomThief Yatagarasu]] before escaping custody. However, Kay claims the Yatagarasu was [[spoiler:her father.]] Turns out neither is quite true. [[spoiler:They were both ''members'' of [[CollectiveIdentity the Yatagarasu]]--as was Detective Badd.]]
* Part of a Jedi test in KnightsOfTheOldRepublic. Two people are suspected of killing a man, when it turns out that both of them intended to do so independently of each other, but one of them (non-fatally) shot the other conspirator by mistake when he thought he was the victim, which allows you to find the truth yourself.
* In the Hidden Object game ''[[VideoGame/MysteryCaseFiles Madame Fate]]'', all of the suspects are revealed to be plotting against the fortune-teller and/or one another. [[spoiler: Subverted; someone else kills Fate -- and all the suspects -- before they can enact their schemes.]]
* The aptly-named "Murder Mystery" quest in ''VideoGame/RuneScape'' was initially not an example of this, as it involved narrowing down one suspect out of six, which varies from player to player. When a sequel was released, however, the earlier quest was {{retcon}}ned into a case of this trope, likely to avoid having to make six different versions of the harder, more complex quest.
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[[folder:Western Animation]]
* PlayedForLaughs in the AllJustADream ''{{Daria}}'' episode "Murder, She Snored", in which Kevin is murdered and Daria is the main suspect. As it turned out, everybody ''but'' her did it, all unaware of each other's plots and thinking they were the sole murderers. Even though they all fess up when Daria starts pointing fingers, [[CrapsackWorld Daria gets convicted anyway.]]
* In the end of the ''WesternAnimation/SouthPark'' episode "Lice Capades", every single student in the class had lice.
* In WhatsNewScoobyDoo the guest stars are chased by an invisible madman and slowly proven that each suspect has an alibi Velma concludes that the ScoobyDooHoax was a group effort by the suspects, using a technology they were developing for the government.
** Also in "Mystery of the Samurai Sword", the Scooby-Doo Rule that "the first fully named character did it" is both played straight and subverted - ALL the named characters are in on the plot.
* Done in an episode of ''ThePJs'', Thurgood takes Calvin and Juicy's homemade go-cart for a ride, and wrecks it in the process. He plays innocent while the residents try to get to the bottom of who broke it. To which each one admits they had taken it for a joyride in some form or another.
* In the ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' episode [[Recap/MyLittlePonyFriendshipIsMagicS2E24MysteryOnTheFriendshipExpress MMMystery on the Friendship Express]], the Marzipan Mascarpone Meringue Madness was partially eaten by [[spoiler:Rainbow Dash, Fluttershy, and Rarity. The other bakers also ate each others desserts.]]
* In ''WesternAnimation/BatmanMysteryOfTheBatwoman'', [[spoiler:all three suspects are [[CollectiveIdentity Batwoman]]]].
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