Fritz Lang's groundbreaking early sound film stars Peter Lorre as Hans Beckert, a child murderer whose crimes terrorize Berlin so thoroughly that both the police and the city's organized criminal underworld launch parallel manhunts to catch him — the criminals wanting him gone before increased police scrutiny disrupts their own rackets. Lang's use of sound, still novel to cinema at the time, becomes a tool of dread itself, particularly Beckert's ominous whistled theme that signals his presence before he's even seen. Lorre's performance, oscillating between menace and pathetic self-loathing, gives the film a moral complexity rare for the era's crime pictures. Widely considered one of the most influential films ever made, it laid essential groundwork for the psychological thriller and film noir.