M (German: M - Eine Stadt sucht einen Mörder) 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. The film has become a classic which Lang himself considered his finest work.
Peter Lorre made film history with his startling performance as a psychotic murderer of children. Too elusive for the Berlin police, the killer is sought and marked by underworld criminals who are feeling the official fallout for his crimes. This riveting early talkie unfolds against a breathtakingly expressionistic backdrop of shadows and clutter, an atmosphere of predestination that seems to be closing in on Lorre's terrified villain. M is an important piece of cinema's past along with a number of Lang's early German works, including Metropolis and Spies.