Giving birth to the police procedural, Fritz Lang’s M, though talky, retains a grim fascination. It is about two city-wide hunts for the same man—one by the police, the other by the underworld, which hopes to put a stop to the police search of which their criminal business is running afoul. The hunted man is a pedophile and serial killer of little girls. When they wrongly suspect someone on the street of being the killer, people become an enraged mob and assault him, taking the law into their own hands, just as the criminals are doing. Moreover, they reflect something of the compulsive killer’s own inability to control himself. Primarily, the film identifies…