The film begins on a foggy night in London after the murder of famous opera singer, Alice Alquist. Her young niece, Paula, having discovered the body, is placed in the hands of a guardian. Twenty years later, Paula has grown up and married pianist Gregory Anton. The couple moves to Paula's ancestral home. Upon seeing the room in which her aunt was murdered, Paula becomes upset.
Strange things begin to happen soon after the move.
The affectionate and doting Gregory loses his temper easily and becomes possessive. He warns her that her memory lapses are becoming unnerving, and reveals that Paula's mother, before her death, was committed to an insane asylum. This alarms Paula because she has been hearing footsteps in the attic and has noticed the gaslights dimming every night. Paula's vitality and happiness dissolve to paranoia and fear. A gossipy neighbor, interested in the strange couple, discusses the Antons with a Scotland Yard detective, Brian Cameron.