The Madness of Crowds
M is very much so the story of a city, and its everyday people are key players. After all, it is the children in these masses who are being preyed upon, and mothers in this populace who are mourning their lost children. But Lang rarely paints a sympathetic picture of his crowds. Instead, we consistently see crowds acting in terrifying ways. They gang up on innocent people in the streets and sit as a raving jury eager to execute a suspect without giving him a fair hearing. Lang clearly sees the madness of crowds as a threat just as great, if not a greater, than a killer on the loose.
The Failure of the Law
Filled with fat cats and ineffective at solving a series of grizzly murder cases, the government in M is mercilessly portrayed as an incompetent body making a big show of doing nothing at all. We sense that the public has no faith in the police to solve the murders, leaving a massive power vacuum for others to take action. Ultimately, the criminal underworld takes on the role of the law, setting up a rigorous investigation of the entire city complete with a corner-by-corner surveillance system by way of the city's street people. As fun as those sequences may be to watch, Lang makes it clear with the distillery courtroom scene that the shadowy figures who assume the role of the law are not necessarily the people we want exacting justice. The way this presages the rise of Hitler's fascist government is deeply chilling.
The Rotting Bourgeoisie
In M, our killer is an inconspicuous citizen dressed like the typical businessman. He is significantly more put together than any of the beggars on the street, and his dress and living quarters suggest that he is fairly well off. Contrast this with Mrs. Breckmann, a salt-of-the-earth domestic figure who is worked to the point of exhaustion and has her daughter ripped away from her by some random evil. Ever the class-conscious filmmaker, Lang uses Beckert to show the hollowness of the bourgeois ideal, and how in this society, the working class suffers while the fat cat government officials smoke and argue with each other, doing nothing to improve the material conditions of contemporary city life.
Darkness Overtaking Light
What scenes transpire during the daytime in M? There are just a few, really. There's after-school sequence including the chilling shots of sun bathing the field where Elsie's ball rolls after her murder. There's also the scene where Inspector Lohmann goes to Beckert's apartment and we see sunlight shine through the window near where Beckert wrote his letter. Aside from that, the majority of M takes place at night. It's a film full of shadows and dark criminal forces fighting against one another. Really, there isn't a single meaning or take away from how darkness plays into M. Rather, M stands as Lang's rumination on the theme.
City Life
Lang's most famous German films—Metropolis, the Doctor Mabuse series, M—are parables about life in the bustling modern city. Remember that the industrialized European city was still a relatively recent phenomenon at that point and that the feel of these places were changing rapidly, with the spread of electric lights and cars. Our first introduction to how the urban setting disrupts the rhythms of human life comes when Elsie is almost struck by a car early in the film. There wouldn't be a film if Elsie were killed by the car and not by Hans Beckert, but Lang makes it clear early on that there's something precarious about this city living. As the city is thrown into turmoil later in the movie, all configurations of city dwellers begin to act in violent masses, be they large groups of criminals or regular people on the street.
Split Personalities
Hans Beckert, of course, is the embodiment of the split personalities theme. Even prior to his glorious monologue about the two men inside of him at the end of the film, we watch him thrown into madness, fighting himself as he becomes overtaken by the desire to pursue his next victim. But Beckert is not the only person with split personalities. We see Der Schräker inhabit the dual roles of gang leader and law enforcer, once as he literally assumes the costume of a police officer and later when he poses as judge in a kangaroo court. Take Franz as well, the sly burglar who breaks down as soon as Lohmann implicates him in a murder. Over and over, Lang shows criminals as men who live two lives simultaneously.
Searching for Justice
So much of this film is dedicated to a hunt for a killer, as an entire city tries to prevent his next murder and exact justice for a series of murdered children. But catching that killer does not end the search. After about an hour and a half of the cat-and-mouse game, Lang puts us into an ad hoc courtroom where Hans Beckert is to be tried in front of a court of underworld criminals. But no justice is to be found here, as both Beckert's assigned defender and Beckert himself make clear. All the court wants is Beckert's head. When Beckert does finally get his day in court, we are still deprived of justice, quite literally. Lang cuts away from the judge about to issue a ruling and gives us Elsie's mother decrying that no sentence will bring the children back. Justice is never served in M, and Lang forces us instead to ask ourselves exactly what we are searching for when we search for justice.
