A jaded, wealthy couple watch a blue movie in their castle home along with her adult son. The son is testy, so they go into town and watch a circus-like thrill ride. The daredevil woman in the show looks exactly like one of the women in the movie, so the man invites her to join them for a nightcap. Tensions among the family seem to rise. She stays overnight, and during her 24 hours in the castle, each of its three residents involves her in a fantasy. She, in turn, keeps asking, "Who has the gun?" Will there be violence before it's over?
Marguerite, a beautiful woman of affairs, falls for the young and promising Armand, but sacrifices her love for him for the sake of his future and reputation.
The film begins when a stranger arrives in town. He takes quickly to his former mistress, Denise, who is happily married to John, and has an affair with his identiske twin brother Peter. They plan together to drive John crazy. After unsuccessful attempts to blackmail the couple receive the stranger, Gert, to help them with their evil plan.
Mike Sturges and his younger brother, Roy, are sentenced to Yuma Penitentiary on a trumped-up train robbery charge. Both endure cruel treatment before Mike escapes to extract revenge on their enemies.
