Loner Mark Lewis works at a film studio during the day and, at night, takes racy photographs of women. Also he's making a documentary on fear, which involves recording the reactions of victims as he murders them. He befriends Helen, the daughter of the family living in the apartment below his, and he tells her vaguely about the movie he is making.
When his mother eloped with an Italian opera singer, Louis Mazzini was cut off from her aristocratic family. After the family refuses to let her be buried in the family mausoleum, Louis avenges his mother's death by attempting to murder every family member who stands between himself and the family fortune. But when he finds himself torn between his longtime love and the widow of one of his victims, his plans go awry.
Miss Marple believes she's seen a murder in a passing-by train, yet when the police find no evidence she decides to investigate it on her own.
