Plot
The film begins by following a tour group at a memorial museum dedicated to Nancy Archer. The patrons are shown a film with Dr. Loeb, who explains that the events surrounding Nancy Archer were true. Nancy's late mother bequeathed her entire estate to her. Her father, Hamilton Cobb, hopes to use the money to gain control over the town they live in. Nancy sees her psychiatrist, Dr. Cushing, about her low self-esteem and bad marriage to Harry Archer. Her husband frequently spends time with a beautiful mistress, Honey Parker, the town beautician, together with whom he discusses his plans to steal the family's business away from Nancy's father. Despite her attempts to confront Harry, Nancy cannot express her anger in a healthy manner, allowing both her husband and father to take advantage of her.
While driving one night out in the desert, she sees a UFO, which shines a bright light at her. She keeps it secret out of concern of becoming a laughingstock, but knows it was real. She finally convinces Harry to accompany her on another night time drive in the desert, but the UFO is nowhere in sight. Suddenly, the ship descends from the sky. Getting out of the car for a closer look, Nancy is trapped by a bright light and disappears along with the UFO. Harry quietly returns to town and does not even report the kidnapping to the local authorities, Sheriff Denby and deputy Charlie.
A dazed Nancy is later found atop Honey's salon and is brought home. Her father is suspicious that Harry left her out in the desert while Harry denies any wrongdoing. Harry accuses Hamilton of neglecting his own wife after she was locked away at a sanitarium (ironically which is what Harry attempted to do after Nancy told him about the UFO). As the two men argue, Nancy loses her temper, shouting that she can speak for herself and her mother. Suddenly, to everyone's surprise, she begins to grow; her clothes tear and rip as her head goes smashing through the ceiling into the attic.
The next morning Nancy is relocated to a large stable. There she is introduced to Dr Loeb. He observed a hormonal surge that occurred during Nancy's growth. Scared, Nancy asks that he find a cure, while keeping it a secret. Unable to convince her to move to a "controlled, therapeutic environment", Dr Loeb explains to Harry that Nancy's condition is unique and precarious. The strain of her heart to sustain her new size would make any stress too dangerous for her. This gives Harry an idea to get rid of her.
As she grows, Nancy becomes more self-confident and strong-willed, empowered by her new strength over everyone else. Eventually, she invites Harry to dinner and discuss her physical, mental and emotional growth. She thinks it will make their marriage stronger and she has a number of other ideas. However, Harry speculates that more stress will overload her heart and blood pressure and that she will die, leaving the family business and its money to him.
Harry, pretending to be unhinged by Nancy's suggestions (but carrying out his plan to overload her heart so that she dies), reveals his affair with Honey as well as earlier flings, deliberately insults and angers her so much that she faints from the stress, crashing into the stable. Escaping to Honey's salon, he celebrates Nancy's apparent death by offering her Nancy's diamond necklace. Nancy wakes up and searches through the town for Harry. She passes a drive-through theater showing Attack of the 50 Foot Woman .
Finding Honey and Harry, she grabs Honey but spares her, telling her she doesn’t have to act stupid. Harry hides under the desk in pure fear. He crawls away, feeling more scared then he has ever felt; Nancy is back for revenge. Trying not to scream or cry, he runs to his car. Nancy follows him and dumps him in her hand. Capturing Harry, she flees into the desert with National Guard helicopters pursuing her. Stopped by some high voltage power lines and confronted by her father and the authorities, she asserts herself and announces her father's ambitions to buy out the town using her money.
Due to a miscommunication from the sheriff a sniper on the helicopter shoots Nancy. Taking a direct hit, she falls onto the power lines, but is rescued and taken away (with Harry still in her grip) by the UFO, proving her claims were real.
The crowds disperse, with Honey making a business agreement with Hamilton. Dr. Cushing explains to the press that wherever Nancy is, she now has Harry all to herself. Inside the UFO, Harry is forced to undergo therapy with two other men under a tiny dome, watched over by Nancy and two other giantesses, and the spaceship flies away into the night.
