Fritz Lang’s tale of a community torn apart and then united by the threat of a child murderer has a lot to say about power in civilisation. The contrast between the police investigation – driven by increasingly draconian measures – and the criminal underworld’s approach to these tragedies demonstrates powerfully how the polite notion of “civilisation” is merely a thin veneer over the mob’s desire for violent retribution.

The message is reinforced by M’s precise photography and editing: the numerous shots of gaping holes rent in office buildings or warehouses demonstrate the violability of social reason, while the cross-cutting between the conferences of police and crime bosses effortlessly highlights the parallels between the two groups. And there’s that perfect, enormously redolent shot of Peter Lorre staring, bug-eyed, at his own terrible reflection, face-to-face with the reality of his moral grotesquery.

Lorre’s performance here is iconic, and deservedly so; he captures the worst impulses of humanity without ever descending into hyperbolic monstrosity. Just as Lang directs with restraint – finding horror in the simple image of an abandoned ball – Lorre manages to simultaneously capture atrocity and sympathy in the one man. He’s so convincing, it’s not surprising he was subsequently typecast as a villain.