| Director | Freddie Francis |
|---|
Janet Freeman, a girl at finishing school who six years earlier saw her mother stab her father to death, is plagued by nightmares. (Her mother, following the tragedy, was committed to an asylum.) Miss Mary Lewis, a teacher, takes Janet home and in the absence of Henry Baxter, Janet's guardian, they are met by John, the chauffeur; Mrs. Gibbs, the housekeeper; and Grace Maddox, an attractive nurse-companion hired by Henry. Miss Lewis leaves Janet in Grace's care.
The nightmares continue: a white-shrouded woman roams the corridors, inviting Janet to burst into her parents' room, where she finds the same woman on the bed with a knife in her chest. When Henry returns, he finds Janet under sedation; her doctors recommend psychiatric care but he refuses and Janet tries to commit suicide.
Henry's wife comes to tea and, because she seems to be the woman in Janet's nightmares, Janet stabs the woman to death and is promptly committed to an institution. The woman in white is revealed to be Grace, disguised with a wig and mask and conspiring with Henry. They marry, but Grace begins believing that Henry is trying to drive her mad. Under the impression that Janet has escaped from the asylum, Grace stabs Henry to death, expecting Janet to be blamed. However, Mrs. Lewis, Mrs. Gibbs and John reveal that they were on to Grace and Henry's plan to drive Janet crazy and decided to get revenge on the both of them and reveals that Janet is recovering well. Grace finally snaps before being brought to justice.