When Miss Marple (Margaret Rutherford) witnesses a murder on a passing train, she reports the incident to police. When the law and railway officials refuse to believe her, she takes a job as a maid to uncover the criminal. She finds the body of the murdered girl before discovering two subsequent victims. Miss Marple must unmask the murderer before the next killing. Story comes from the Agatha Christie novel "4:50 From Paddington."