One of Hitchcock's most frequent techniques was to have his characters get caught up in a web of confusion and chaos that is totally beyond their control. That concept works so very well because most people can readily identify with it. In Murder, Diana Baring is an actress who is caught standing over the corpse of a fellow actress. Even worse, she has amnesia and remembers nothing about the murder, or herself. Though she desperately tries to recall anything that can clear the fog from her mind, her amnesia is complete, as is the evidence against her. She is convicted of murder and sentenced to die. Only one person believes she is innocent, but can he prove it in time to save her?
In addition to many inventive cinematic techniques created by Hitchcock for Murder was the director's presentation of a character's thoughts on the soundtrack, the first time this had been done in a sound film. Hitchcock achieved this effect by improvising brilliantly: he had Marshall prerecord his lines on a wire tape recorder, and the director played the recording back while shooting a scene of the silent Marshall shaving. Behind the bathroom wall was hidden a live 35-piece orchestra playing the prelude to "Tristan and Isolde," the music supposedly coming from the radio.