New York City novelist Lauren Cochran (Robin Groves) suffers from agoraphobia and, in a bid to overcome her ailment, she rents a stately Victorian mansion in the country from a scientist, Daniel Griffith (Michael Lally) and his ailing grandfather, Colonel Lebrun (John Carradine). A series of strange occurrences begin once Lauren moves in; when she meets Col. Lebrun, he suffers a stroke at the sight of her, and she suspects that the house may be haunted after suffering bizarre dreams of women lounging around the house. She also feels she has seen the home before, and realizes an illustration of it appears on one of her novels, entitled The Nesting.
One day, while investigating the turret at the peak of the house, Lauren becomes trapped outside on the window ledge, and has a vision of a woman inside. Her psychiatrist, Dr. Webber, arrives at the house, and is killed while attempting to save her. Several days later, Lauren is attacked by Frank Beasley, a handyman, at the house. Amidst the attack, he begins to levitate, and flees the house in terror; he has a vision of two women’s corpses lying in his truck, and he flees into the woods, and stumbles into a pond, where he is dragged under by ghostly hands and drowns.
Lauren, bothered by the events occurring in the house, visits a local man, Abner Welles, to ask about the house after having heard Frank mention his name. Abner, a drunk with a bad reputation in town, becomes erratic and violent when she inquires about the house’s history, and chases her away in his car. The two get into a car accident, and Lauren flees on foot and hides in a barn. Abner finds her, and attempts to attack her with a pitchfork, but it is torn from his hands by an unseen force. Lauren then stabs him through the head with a scythe, killing him.
Lauren’s visions in the house become increasingly bizarre, and she begins having precognitive dreams. It is revealed by Col. Lebrun to Daniel that the home was a former brothel during World War II, and that Frank and Abner murdered several prostitutes and soldiers in the home and dumped their bodies in the nearby pond.
At the house, Lauren has an intense hallucination, in which she meets Florinda (Gloria Grahame), the madame of the brothel, and it is revealed that she is Florinda’s granddaughter and, as an infant, was the lone survivor of the murders in the home. At the end of the film, she experiences a vivid hallucination in which her manuscript begins burning, and she witnesses Frank’s truck crash into the house, and catch fire. At the end of the vision, she comes back to reality, and stumbles out of the house at dawn.