M is a 1931 German drama-thriller film directed by Fritz Lang and starring Peter Lorre. It was written by Lang and his wife Thea von Harbou and was Lang's first sound film. He had directed more than a dozen films previously. A group of children are playing an elimination game in the courtyard of an apartment building in Berlin using a chant about a child murderer. A woman sets the table for dinner, waiting for her daughter to come home from school. A wanted poster warns of a serial killer preying on children, as anxious parents wait outside a school. Little Elsie Beckmann leaves school, bouncing a ball on her way home. She is approached by Hans Beckert, who is whistling "In the Hall of the Mountain King" by Edvard Grieg. He offers to buy her a balloon from a blind street-vendor. He walks and talks with her. Elsie's place at the dinner table remains empty, her ball is shown rolling away across a patch of grass, and her balloon is lost in the telephone lines overhead. In the wake of Elsi...