Murder Most Foul represented Margaret Rutherford's third appearance as Agatha Christie's spinsterish sleuth Miss Marple. The film opens with Marple serving on a murder-trial jury. She forces a mistrial because she considers the accused to be innocent; to prove her theory, she traces the trail of evidence to a down-at-the-heels repertory company run by Ron Moody. She auditions for the troupe with a stirring rendition of "The Shooting of Dan McGrew," securing the job by flashing a roll of bills in front of the covetous Moody. While snooping about backstage, Miss Marple discovers both murderer and motive-and, as is customary in the "Marple" films, she nearly loses her own life in the process. Based on the Agatha Christie novel Mrs. McGinty's Dead, Murder Most Foul co-stars Margaret Rutherford's real-life husband Stringer Davis as Marple's friend and confidante Mr. Stringer.