[[quoteright:261:http://static.tvtropes.org/pmwiki/pub/images/M_poster.jpg]]
-->Just you wait, it won't be long.\\
The man in black will soon be here.\\
With his cleaver's blade so true.\\
He'll make mincemeat out of ''you''!

Creator/FritzLang's 1931 masterpiece about a serial child killer in Weimar Berlin and the people who try to find him: the police, the criminal underworld, and the city's beggars. One of the first examples of FilmNoir, ''M'' provides not only stark black and white images, but also a haunting {{leitmotif}} throughout the film.

Hans Beckert (PeterLorre) whistles "In the Hall of the Mountain King", as he buys a balloon from a blind balloon seller for a little girl named Elsie Beckmann. A scene later, Elsie's mother looks for her and can't find her, shouting her name as the camera shows the balloon drifting in the sky.

Police inspector Karl Lohmann, meanwhile, is investigating the serial killings with modern policework, such as fingerprinting and handwriting analysis. The criminal underworld, too, is searching for the killer, since more police on the street is bad business for them and they, too, [[EvenEvilHasStandards are disgusted by the killer targeting children.]]

When Hans whistles "In the Hall of the Mountain King" again in front of the blind balloon seller, the seller tells one of the criminals, who marks Hans with a chalk M on his jacket, so they can follow him. The criminal fraternity goes to more ruthless lengths than the police to catch the killer, and cause a great deal of collateral damage to people and private property, before finally closing in on him. The criminals kidnap Beckert and bring him to a KangarooCourt, where Hans makes an impassioned speech about how he should not be blamed for the murders since he can't help himself, he can't help that he's insane. Despite the nature of the court, the criminal appointed as Beckert's legal representative tries hard to defend him fairly. The 'prosecutor' takes the stance that either for his crimes (if he is not insane) or for his insanity, Beckert has forfeited his right to live and must be exterminated. Beckert desparately tries to he explain that ''he can't help being this way''. The criminals are about to kill Hans when the police bust in and arrest both him and his captors.

As Hans is about to be sentenced by five judges, the mothers outside the courtroom say it won't bring back their children. Elsie's mother says they should have kept better watch. [[SomeAnvilsNeedToBeDropped "We have to keep closer watch over the children]]. ''All of us.''"

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!!The film contains examples of:

* AdultFear: Don't leave your kids alone even for a second.
* AntiVillain: Hans.
* ArcWords: "Who is the murderer?"
* BadAssLongCoat: Der Schränker's leather overcoat. Although see PuttingOnTheReich below; he's not a very likable character.
* CharacterSignatureSong: Hans Beckert always eerily whistles EdvardGrieg's "In The Hall Of The Mountain King" when he goes somewhere.
* DramaticDrop: When Franz tells Inspector Lohmann that they broke into the office building to catch the child murderer, the cigar he was smoking falls out of his mouth.
* DreamMelody: "In the Hall of the Mountain King"
* DownerEnding: Beckert is brought to trial, but the climax establishes that neither execution nor medical treatment seem to be a totally fitting sentence, and it won't bring back the kids anyway.
* EmpathyDollShot: One of the [[UrExample oldest examples]]: Elsie's ball and balloon in the opening scene.
* EvenEvilHasStandards: A complicated example. Hans disgusts all the criminal bigwigs because he kills children, but they're only after him because he interferes with their crimes. The "defense attorney" notes the hypocrisy of wanted murderers standing in judgment of another murderer. Hans' final speech also [[MoralMyopia calls them out on their hypocritical "standards"]], pointing out that he does what he does because he is insane and cannot help himself, whereas they simply can't be bothered to learn an honest trade.
* ExtraExtraReadAllAboutIt: "Extra! Extra!", shout all the paperboys carrying news of the Beckmann murder.
* EveryoneCallsHimBarkeep: Der Schränker ("The Safecracker").
* GermanExpressionism: A late example.
* GollumMadeMeDoIt: Beckert's defense. He's driven by a compulsion that he can't resist.
* GoryDiscretionShot:
** Interesting version; In one scene, the Thieves are torturing a watchman for information in a glass-windowed room, with a crowd of beggars watching from outside. When the leader signals for the torture to start, the beggars move up against the windows so nothing can be seen.
** Also, Elsie's death at the beginning.
* TheGreatDepression: A rare European example.
* GreyAndGrayMorality: Even the child murderer is not without his sympathetic side.
* HoldingTheFloor: Beckert's long speech at his trial.
* IneffectualSympatheticVillain: Hans again. In fact, Peter Lorre was typecasted as this role for years afterward.
* InsanityDefense: The climax features an analysis of whether it's fair to punish a man for crimes he was compelled by insanity to do.
* IronicNurseryRhyme: The children's singing in the beginning and "In the Hall of the Mountain King" to an extent.
* JokerJury: The criminals' court at the end (although Hans is far from a hero).
* {{Leitmotif}}: "In the Hall of the Mountain King" used for creepy effect. [[TropeCodifier In fact, ''M'' practically created the cinematic leitmotif.]]
* KangarooCourt: The criminal underworld sets up a court to try Beckert, but it's clear from the beginning that they have no intention to do anything but kill him.
* MatchCut: A crime boss talks to his fellow crime bosses about the problems the child murderer is causing, due to the increased police presence. With a sweep of his arm, he says "I invite--". Cut to another person at a different meeting, sweeping his arm and saying "--your views, gentlemen." The second meeting is a different group of crooks discussing the same subject. The rest of the scene continues to cut between three different meetings in a similar way.
* MurderersAreRapists: Very, ''very'' subtly implied, and all off-screen. One of the police departments on the child-killer case is a sexual crimes division, and one policeman says to another concerning the child-killer's victims "You know what state we find them in after that." Also, everyone was specifically looking for a male perpetrator.
* NeighborhoodFriendlyGangsters: Deconstructed. The vigilante criminals are only interested in ending the manhunt to restore their criminal endeavors. Hans also points out that their crimes have even less justification than his own.
* NoCelebritiesWereHarmed: Lohmann in his bodily build, mannerisms and modus operandi is very closely modeled on Ernst Gennat (1880-1939), the head of Berlin's ''Mordinspektion'' (set up in 1926, the world's first murder squad, i. e. police section specializing in the investigation of murders), who introduced many innovations to investigation procedures and who among other things headed the investigation of the Grossman and Kürten murders and who may have coined the term "serial killer" with reference to the latter. In his day Gennat was internationally famous and known to Berliners by affectionate nicknames like "the Buddha of the Alex" (i. e. the police headquarters on ''Alexanderplatz'').
* NoEnding: Not only does the movie [[TheUnreveal come to a close right before Hans is given a verdict]], but because of the era it was created in ''there aren't even any credits.'' The film just suddenly stops.
* NotSoInnocentWhistle: The killer has a super-creepy whistle.
* OhCrap:
** The climactic moment when the Mob are just about to tear Beckert to shreds, but all of them come to a dead stop and slowly raise their hands in surrender when they realize who's standing on the stairs.
** Before that, the very slow pan around the room after Hans is shoved down the stairs, showing the JokerJury staring at him in unmoving complete silence.
** And, of course, the famous scene where he realizes his coat has been marked and that he's being followed. In fact, this is mostly Beckert's reaction throughout the entire second half of the film.
* OrganGrinder: One is among the beggars tasked with keeping their eyes out for the murderer.
* OneLetterTitle: The "M" stands for ''Mörder", aka murderer.
* OutOfGenreExperience: For a few minutes, the police procedural part switches into documentary style, complete with voice-over, diagrams, and a giant compass drawing circles on a city map.
* PaedoHunt
* PoliceProcedural: The police part of the movie is possibly the [[UrExample ur-example]] of this trope.
* PuttingOnTheReich: A fairly prophetic example, since the Nazis weren't in power yet, Der Schränker's long leather coat, leather gloves and bowler hat nonetheless invokes the fashion sense of already-rising propagandist Joseph Goebbels (and later, the {{Gestapo}}). Somewhat fittingly, the actor was very popular with the Nazis, though he himself was probably not one. The film was originally titled "The Devil Among Us" as a deliberate reference to the then-up and coming Nazi Party. Unfortunately, they figured it out and Lang was forced to change it.
* TheReasonYouSuckSpeech: In his impassioned defense, Hans is quick to note the essential hypocrisy of the court of criminals trying him; he does bad things, but he commits abhorrent acts because he is insane and cannot make himself stop, but they ''choose'' to be criminals when they could instead earn an honest living.
* SilenceIsGolden: Because a silent film was expected to have accompaniment throughout this film is actually quieter than most ''silent films''. The silence of shots like the slow reveal of the mob backed court, and, later, the police coming to stop the mobsters from killing the serial killer makes them so much tenser.
* SerialKiller: Of little girls.
* ShamingTheMob: This is what Hans tries to do. It doesn't work. Except on the audience.
* StabTheSalad: After luring in his next victim, Hans pulls out a switchblade, which he uses to cut an orange.
* SympatheticMurderer: Hans turns out to be one in the end, in spite of his horrific crimes.
* TalentDouble: Peter Lorre couldn't actually whistle, so Lang provided it in a hidden CreatorCameo.
* ThievesGuild: Several of them, it seems, one for each major division of the trade.
* TragicVillain: Hans can't help the fact that he's a child murderer.
* TropeMaker
* TheUnreveal: Beckert's sentence. The judges are just about to announce it when the film cuts to a mourning mother, who says it doesn't matter, because it won't bring back her child.
* VehicleVanish: One of the first examples?
* VeryLooselyBasedOnATrueStory: Fritz Lang based the story on several serial killers who had plagued Germany in recent years, including Fritz Haarmann, Karl Grossmann, and Peter Kürten, the "Vampire of Düsseldorf." Haarman and Grossmann are mentioned by name, and Haarmann is the real subject of the children's rhyhme at the beginning. It should be noted that Fritz denied it because it was seen as being tastelessly (for presenting him as sympathetic) RippedFromTheHeadlines.
* VillainProtagonist: Hans Beckert, serial child murderer.
* WeimarRepublic: In its later years.
* WeirdTradeUnion: The Beggars' League (taken from [[Creator/BertoltBrecht Brecht]]'s ''Theatre/TheThreepennyOpera'').
* WhatIsEvil: Beckert is pursued by the city's criminal underworld, because the intensive police manhunt is interfering with their business and because they resent police inquiries that imply that they might be associated with a child murderer. When they [[JokerJury conduct a mock trial]] of Beckert, he [[ShamingTheMob attacks]] their sense of [[EvenEvilHasStandards moral superiority]], declaring that he does what he does because he's haunted by unwanted compulsions he can't resist, while they do what they do because they freely chose crime instead of honest work.
* WritingIndentationClue: The murderer writes a letter to the newspaper, using a single sheet of paper, a pencil and a wide windowsill in his apartment as a desk. When the police raid the apartment, they find a partial impression of the words in the letter in the wood. In this case, they already knew what had been written; the indentations were, instead, proof of ''who had written it''.
* WouldHurtAChild: Ugh.

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