Description: M is a 1931 German drama-thriller directed by Fritz Lang and written by Lang and his wife Thea von Harbou. It was Lang's first sound film, although he had directed over a dozen films previously, including Metropolis. Over the years the film has become a defining classic that rivals Lang's other works for the title of magnum opus. Lang himself maintained that this film was his finest work. The lead, Peter Lorre, was typecast for years after the film's release as a villain for his portrayal of a child murderer. M also pioneered the use of leitmotif to give the film score a more intense feel.