M is the perfect antidote to the desensitising overload of newspaper reports that dwell ghoulishly on the last hours of child murder victims. There is mercifully little about the murders themselves. Rather, Lang shows us the effects of the killings on the inhabitants of Berlin. The opening scene shows a singing game influenced by the murders that have been taking places, which involves the children dropping out one by one as the murderer gets them. A laundry woman scolds them, before delivering a basket of washing to a mother who is waiting for her daughter, Elsie Beckmann, to come home. When she realises this is not going to happen, there is a shot of the tenement stairwell, washing hanging out to dry in a dark and empty attic, then of an empty chair at the table that has been laid for Elsie's supper.
But M doesn't only dramatise the effect of the crime on the child's mother. It also satirises the hysteria generated in society at large by the resulting climate of fear and suspicion, a theme that also resonates with contemporary viewers. We see an old man surrounded by a baying mob after a little girl asks him the time, reminding one of the vigilantes a few years back, who attacked the home of a 'paediatrician' in Portsmouth. In their haste to make an arrest, the police raid the haunts of the town's criminal and semi-criminal fraternity. This disruption of their 'business' leads the underworld to hunt down the killer, themselves, using their own unorthodox methods...
The manner in which the murderer is identified and hunted allows Lang to demonstrate his grasp of cinema's power, not only as a visual medium, but also with the newly added element of sound. Thus it is a blind balloon seller who recognises the killer's trademark whistling of Grieg's Peer Gynt, from when he bought a balloon to lure Elsie Beckmann to her death. Lack of an incidental score often makes early talkies seem incomplete. But in M the shortage of music is no disadvantage. On the contrary, it makes the city streets seem unnaturally quiet and deserted, as if under curfew. This oppressive silence only emphasises the murderer's eerily hesitant whistling in a macabre parody of the Pied Piper.
The chalked 'M' stamped on his back by the hand of one of his pursuers provides the cinema with one its most potent images. Another is Peter Lorre spotting the mark on his reflection in a shop window, the image of a man hunted not just by an outraged society, but also by his own murderous desires. Lorre does not shrink from making the serial killer repulsive, but his characterisation is also pitiable. He has almost no dialogue for most of the film, and his moon face is first shown gazing into a mirror, at first slack and apparently lethargic, then pulling at the corners of his mouth, his eyes bulging maniacally.
Perhaps the only flaw in this study in deviancy is the unresolved discrepancy between the seemingly untouchable killer suggested by the impotence of the authorities at the beginning of the film, and the abject figure who is revealed to be behind the multiple murders. This contradiction is partly intentional: at first we see a looming, impossibly large shadow, but we soon realise that it has been cast by the short, rotund figure of Lorre. This child murderer seems himself like a little boy in a man's body, a nightmare cross between Peter Pan and Billy Bunter, often haunting toy and sweet shops.
Later, at his arraignment before the rough justice of the Berlin underworld's kangaroo court, we hear his impassioned speech about the compulsions that drive him to murder resemble a toddler tantrum. He speaks of being hunted by his own murderous alter ego, and his account of his murders suggests that they take place during blackouts. However this seems at odds with the shadowy serial killer sending taunting letters to the press at the beginning of the film. Such calculated efforts to spread panic do not seem the work of the same man who later expresses remorse at his actions. Of course, it's possible that he is only putting on a show of contrition to save his skin, but that only adds to the temptation for the viewer to join his captors in their cynical derision.
The DVD special edition is a two-disc package, and extras include: audio commentary; the restoration of M featurette; audio interview - Peter Bogdanovich with Fritz Lang; interview with restoration supervisor Martin Koerber; documentary The Hunt For M; Fritz Lang documentary; visual essay by film historian R. Dixon Smith; extensive stills; set designs; comparison between 1931 version and postwar releases.