Summary
Back at the police station, Inspector Lohmann gets ready to interrogate Franz to figure out why exactly there was a break-in at the office building. After all, nothing was stolen. Lohmann is apparently well-acquainted with Franz already, and knows that if there's one thing that Franz despises, it's needless death. So Lohmann decides to lie to Franz and tell him that one of the security guards was killed during the heist.
When Lohmann goes in to talk to Franz, he says that Franz will be charged with accessory to murder. Franz caves instantly. He may be proud of being a skilled burglar, but he wants nothing to do with dirty tricks. Franz seemingly assumes that Lohmann knows why he was in the office building, unaware that Lohmann is simply trying to make sense of why a break-in occurred at all. In a panic, Franz offers to tell Lohmann where they are keeping the child murderer. Lohmann is totally shocked. He had no idea that the gang was trying to apprehend the murderer and, miraculously, he finally has a break in the case.
The gang has, in fact, brought Beckert to the cellar of an abandoned distillery. This is not where they are holding him, but instead where they will try him, by mob law. By the time he arrives, Schränker has changed out of his police get-up into his more typical uniform, complete with those black gloves. There's a hungry crowd confronting Beckert, and we learn that these people will be the jury in an ad hoc trial that Schränker is conducting. That trial has even come with a court-assigned defense attorney.
It's clear that Schränker has no interest in conducting a fair trial. The appointed defense attorney quickly realizes as much, and demands that Beckert be turned over to the police so that he can face a fair trial, as is his right. Schränker and the jury argue that Beckert gave up his right to a fair trial when he started murdering children. They fear the court would simply deem him insane, send him to a mental institution, and soon enough let him free to wander the streets and start killing again.
Beckert does not contest the idea that he is of unsound mind, and therefore should not be tried as a sane man. In fact, he embarks on a gut-wrenching monologue about the two men inside of him: the killer, and the man who is terrified of that killer. As if possessed by a demon, Beckert describes the voices he hears that tell him to kill, the struggle he has to keep control of himself, the way he blacks out when he begins to kill, the horror he feels when he hears the children scream in agony. The crux of Beckert's self-defense is that he deserves pity because he can not control his actions, unlike the people in the jury who choose the criminal lifestyle over a law abiding one.
The crowd, of course, is having none of it, and Schränker quickly resolves that Beckert will be sentenced to death. Just when the mob beings to descend on Beckert, they freeze and put their hands up. The police have arrived to apprehend Beckert.
We close on a courtroom scene, where a judge is about to make a ruling on Beckert's case. But we do not hear the ruling. Instead, we hear Mrs. Breckmann say that no court decision will bring the children back, resolving that people must take better care of their children.
Analysis
Pursuing the idea that M stands as an allegory for the Weimar Republic's collapse, we can watch the final act of this film as one where law and order have been turned totally upside down. If Lang was trying to weave any sort of moral into M, it likely isn't one about murder or gang activity or caring for the children. No, if Lang is laying down a moral it's one about the danger of a society where faith in the law has collapsed, creating a power vacuum where a taste for blood has replaced a taste for justice.
It's in this final act that we see the extent to which the law has broken down. When Franz tells Inspector Lohmann that the criminals have apprehended the child murderer, Lohmann reacts more like a Keystone Cop than a police chief in a movie about a child predator. He makes a series of zany faces and loses breath, only to compose himself and act like he knew all long that Franz could tell him the location of the killer.
In this moment, Lang makes it crystal clear why the criminals were so compelled to take matters into their own hands. The cops could barely recognize a good lead when it fell into their laps. But the criminal-led court scene that we're shown is not a positive alternative. In fact, Lang very effectively establishes that if there is justice to be served, it is not in this scenario.
Again, Lang does that through a combination of good-old film-making chops, by giving the defense attorney and Beckert closer angles during their monologues than he ever does of Schränker or the raving crowd. This humanizes Beckert more than his prosecutors.
But he also does it through a masterful maneuver that he's been teasing us with throughout the film. With that incredible monologue that Beckert recites, pleading for his own life, Lang finally gives this potentially-monstrous character complexity. Notably, Beckert is the only character in the entire film whom Lang has lent more than one side. Most of the other characters are stock figures: Franz the hapless burglar, Mrs. Breckmann the worried mother, and so on. With Beckert's monologue, Lang finally breaks this pattern of rendering each character as one-dimensional, and we learn that no matter how ghastly this human is, he is still human.
This is what makes the payoff of the scene's final lines really hit. We've gone through this whole journey watching this killer on the prowl, hoping just as intently as everyone else in the film that he would be caught. But at the end of the day, there's no real justice for the victims. They are dead, and they aren't coming back. With all of this, Lang asks what we really get from exacting revenge on society's lowest. Does it make our society stronger, or does this thirst for revenge just corrode the order that law is supposed to foster?
