Heiress Elaine Wheeler is haunted by the horrific memory of her first husband's affair and death, both of which she discovered at the same time. Afflicted with lifelong insomnia and aimlessly wandering her New York City townhouse one night, she sees something horrific in the building across the street. But nobody can find any evidence that what she saw actually happened. Her tender husband John and best friend Blanche try to convince Elaine that she is letting her nerves get the best of her, but the eccentric neighbour Appleby and testy German maid Helga start to hint that what is going on may not be what it seems.