M (1933)

A German city is blanketed in a state of fear when serial killer Hans Beckhert (Peter Lorre) murders nine children in the span of a year. Inspectors Karl Lohman (Otto Wernicke) and Groeber (Theodor Loos) lead the exhaustive investigation to catch the killer, but come up short.

The public begins to feel frustrated and helpless, but they aren't the only ones. The city's local criminals are fed up with the crackdown the police are enforcing in their underground crime circles and decide to take the law into their own hands.