“M – Eine Stadt sucht einen Mörder” (translated as “M – A City Searches for a Murderer”) is a German film directed by Fritz Lang, released in 1931. It is a suspenseful thriller and is considered a masterpiece of German cinema.

The film follows the investigation of a serial killer who preys on children in Berlin. The killer, played by Peter Lorre, is hunted down by both the police and the criminal underworld, who are determined to catch him and bring him to justice. The film is notable for its use of sound design, with the haunting whistle tune used by the killer becoming a recurring motif throughout the movie.

“M” is considered a groundbreaking film in the history of cinema and has influenced many other films and filmmakers since its release. It is often cited as a classic example of German Expressionist cinema and has been praised for its themes of morality, justice, and the nature of evil.