After the death of her famous opera-singing aunt, Paula Alquist (Ingrid Bergman) is sent to study in Italy to become a great opera singer as well. While there, she falls in love with the charming Gregory Anton (Charles Boyer). The two return to London, and Paula begins to notice strange goings-on: missing pictures, strange footsteps in the night, and gaslights that dim without being touched. As she fights to retain her sanity, her new husband's intentions come into question.