In 1957, the Dollanganger family—father Christopher, mother Corrine, 14-year-old Chris, 12-year-old Cathy, and 5-year-old twins Carrie and Cory—enjoy an idyllic life in Gladstone, Pennsylvania, until tragedy strikes when the father dies in a car accident, leaving Corrine in debt with no way to support the children. The sudden hardship sets a dangerous plan in motion, as Corrine resolves to return to Foxworth Hall in Virginia to win back the affection of her father and secure a place in his will.
On the verge of foreclosure, Corrine reveals to the children that, as a young woman, her marriage to Christopher so offended her multimillionaire father Malcolm Foxworth that he disinherited her. Now elderly Malcolm is dying of heart disease, and Corrine intends to reclaim his favor to be reinstated in the will. Because Malcolm is unaware that Corrine had children by her marriage to Christopher, the children must hide in a secluded upstairs room of Foxworth Hall until Corrine can break the news to her father. She assures the children that they will only be in the room for a few days.
At Foxworth Hall, the Grandmother locks the children in a bedroom connected to the house’s large attic. The Grandmother forces Corrine to reveal to her children that the reason for disinheritance was that Christopher Sr. was Malcolm’s younger half-brother, thus Corrine’s half-uncle, and that the children are the products of incest. The Grandmother believes the children are “the Devil’s spawn” and is obsessed with the idea of incest, forbidding all contact between opposite sexes, while prohibiting the children from making noise or opening the room’s windows. Only in the attic are they free to play.
Chris and Cathy try to make the best of the situation, decorating the attic with paper flowers to create an imaginary garden for the twins. Corrine visits several times a day, bringing toys and gifts, but over time her visits become sporadic. After months pass, Chris and Cathy confront her, as she promised they would be freed in only a few days. Corrine finally confesses that they must remain in the room until their grandfather dies.
A year later, Chris and Cathy have both entered puberty, while the twins are stunted from inadequate nutrition and lack of sunlight. With no other outlets, Chris and Cathy develop a romantic and sexual attraction toward each other, though they do their best to deny their feelings. The Grandmother catches Chris staring at a half-dressed Cathy and punishes the children by cutting off their food supply for over two weeks, while they pray their mother will reappear in time to save them. On the verge of starvation, Chris and Cathy decide to escape with the twins to find help. Before they can go, though, the Grandmother begins bringing food again, including a rare treat of powdered-sugar doughnuts. Soon afterwards, all the children begin to complain of constant minor illness.
Another year passes. After an absence of several months, Corrine visits the children, explaining that she has been on a European honeymoon with her new husband, Bart Winslow. Chris and Cathy are furious, but fear Corrine will abandon them permanently if they confront her. Realizing that the twins’ health is declining, he and Cathy decide to escape. Chris creates a wooden skeleton key. Over the next several months, he and Cathy take turns slipping downstairs to Corrine’s suite to steal cash and jewelry to fund their lives outside. One night, Cathy comes across her sleeping stepfather and kisses him. When Chris learns of the kiss, he rapes Cathy in a fit of jealousy and rage. Afterwards, he is overcome with remorse, while Cathy feels guilty and conflicted about the act due to her love for Chris.
One of the twins, Cory, becomes deathly ill. Cathy begs Corrine to take him to a hospital, but Corrine hesitates. Enraged, Cathy tells her that if she does not act to save Cory’s life, Cathy will reveal their existence to the grandfather. Corrine finally takes Cory away but returns the following morning to inform the children that he died of pneumonia. The children are devastated, with Cathy left wondering if Cory’s death is God’s punishment for her sexual assault by Chris.
Chris resumes stealing from Corrine’s rooms, only to discover that Corrine and Bart have left Foxworth Hall permanently. Eavesdropping on the servants, Chris learns that their grandfather died a year ago and that the Grandmother has been leaving food contaminated with rat poison in the attic due to a “mouse infestation.” He connects this with the doughnuts they are being fed, and realizes that Cory died of arsenic poisoning.
The three remaining children finally leave Foxworth Hall to catch a train to Florida. At the station, Chris reveals that he discovered Corrine’s inheritance is conditional upon her having no children from her first marriage, and Corrine, rather than the Grandmother, was the one who most likely poisoned them. Chris and Cathy decide against contacting the authorities, as their main concern is to stay together, but Cathy vows that one day she will make Corrine pay for her crimes.
