Early Alfred Hitchcock film starring Ivor Novello, based on a story by Marie Belloc Lowndes and a play Who Is He? co-written by Belloc Lowndes, concerning the hunt for a serial killer in London. According to Hitchcock scholar Donald Spoto the film is "the first time Hitchcock has revealed his psychological attraction to the association between sex and murder, between ecstasy and death." The film also features Hitchcock's first recognizable film cameo, something which was to become a standard practice for the remainder of his films.