"M" (1931)

It's unusual for a seventy-five year old film to maintain any vitality but Fritz Lang's "M" manages just that. Co-written by Lang and his wife Thea von Harbou this tale of a serial child murderer stalking city streets undetected offers a highly watchable film without basking in the sordid theme. Rather it holds relevance to modern viewers, but more thoughtfully than anything you're likely to see, read or hear now.
The lead was Peter Lorre's first role, masterfully played with the natural creepiness which he became so famous for. Every moment he's on screen is a delight with his expressive acting owing more to silent pictures but gently blessed with the addition of sound.
The other acting is high quality, the photography superb; murders are only hinted at with simple visual metaphors, such as lunch set at table but lacking child, while the style is pure noir.
When released it was highly influencial, partly because it was one of Germany's first films with sound but also because German film enjoyed a great reputation between the wars similar to that enjoyed by modern French cinema today.
Hitler's rise to power and the decimation of the creative industries led to both Lang and Lorre moving abroad, a wise move considering images from "M" appeared in the Nazi propaganda film "Der Ewige Jude" (The Eternal Jew) as an example of the contortion of "the normal sense of Justice".
I've avoided giving away the twists and turns of plot because my meagre words can't match the celluloid tale, and it's far too good to spoil. "M" has been restored by Eureka, is available on DVD and is rated PG.