Attorney Anthony Keane (Gregory Peck) agrees to represent Londonite Mrs. Paradine (Alida Valli), who has been fingered in her husband's murder. From the start, the married lawyer is drawn to the enigmatic beauty, and he begins to cast about for a way to exonerate his client. Keane puts Andre Latour (Louis Jourdan), the Paradine household servant, on the stand, suggesting he is the killer. But Keane soon loses his way in the courtroom, and his half-baked plan sets off a stunning chain of events.