Fritz Lang's chilling masterpiece about a serial child killer who terrorizes a German town, Peter Lorre gives an unforgettable performance as the modern psychopath, Franz Becker, who attempts to attain the dignity of a tragic hero, despite his uncontrollable urge to kill. Often credited for starting both the serial killer and the police procedural film genres, M is also notable for its startling statement about the murderous nature which resides within human beings.