Wealthy industrialist Jacques Decret discovers his wife Gloria's infidelity with a young actor. Fueled by jealousy, he unleashes a campaign of anonymous letters that mislead her into believing her lover is behind the harassment. As the psychological torment escalates, Gloria finds herself trapped in a web of deceit and desperation, searching for a way to escape the escalating chaos of her life. The tension between them mounts, revealing the destructive power of jealousy and manipulation in their shattered relationship.