Suffering from headaches and inexplicable blackouts, timid housewife Eve White (Joanne Woodward) begins seeing a psychiatrist, Dr. Luther (Lee J. Cobb). He's stunned when she transforms before his eyes into the lascivious Eve Black, and diagnoses her as having multiple personalities. It's not long before a third, calling herself Jane, also appears. Through hypnosis and continued therapy, Luther struggles to help Eve recall the trauma that caused her identity to fracture.