Unable to sleep, Elaine Wheeler paces the living room of her Manhattan townhouse, troubled by unsettling memories and vague fears. Her husband tries to comfort her, but when he steps away for a moment, Elaine screams as she sees (or believes she sees) the body of a dead man in the window across the way. The police find nothing except an empty chair. Elaine's terror grows as, shortly thereafter, she sees another body—this time a woman's—but by now the police are skeptical and pay no heed to her frantic pleas. Her husband, claiming that Elaine may be on the verge of a breakdown, calls in a psychiatrist, who agrees with his suggestion that Elaine should commit herself to a sanitarium for treatment. The plot moves quickly and grippingly as those involved—Elaine's old friend and house guest Blanche; the inquisitive and rather sinister man who lives next door; and the nosy German maid Helga—all contribute to the deepening suspense as the play draws towards its riveting and chilling climax.