|Portrayed By:||Allison Hayes|
Nancy is a rich but troubled woman with a history of emotional instability and immoderate drinking, is driving on a road that night in an American desert. A glowing sphere settles on the deserted highway in front of her, causing her to veer off the road. When she gets out to investigate the object, a huge creature exits and reaches for her.
Nancy escapes and runs back to town, but nobody believes her story due to her known drinking problem and a recent stay in a mental institution. Her philandering husband, Harry Archer, is more interested in his latest girlfriend, town floozy Honey Parker. He pretends to be the good husband in the hope that Nancy will "snap" and return to the "booby hatch," leaving him in control of her $50 million estate.
Nancy bargains with Harry, asking him to search the desert with her for the "flying satellite," agreeing to a voluntary return to the sanatorium if they find nothing. As night falls, they find the spacecraft and the alien creature emerges, revealed as an enormous male human. Harry fires his pistol at the giant, but the gunfire has no effect. Harry flees, leaving Nancy behind.
She is later discovered on the roof of her pool house in a delirious state and must be sedated by her family physician, Dr. Cushing. The doctor comments on scratches he finds on Nancy's neck, and theorizes that she was exposed to radiation. Egged on by his mistress Honey, Harry plans to inject Nancy with a lethal dose of her sedative, but when he sneaks up to her room, he discovers that she has grown to giant size. In a scene paralleling Nancy's first alien encounter, only an enormous hand is seen as Harry reacts in horror.
Cushing and Dr. Von Loeb, a specialist brought in by Cushing, are at a loss on how to treat their giant patient. They keep her in a morphine-induced coma and restrain her with chains while waiting for the authorities to arrive. The sheriff and Jess, Nancy's faithful butler, track enormous footprints leading away from the estate to the alien sphere. Inside the sphere, they find Nancy's diamond necklace (containing the largest diamond in the world) and other large diamonds, each in a clear orb. They speculate that the jewels are being used as a power source for the alien ship. The huge human reappears, and the sheriff and Jess flee.
Meanwhile, Nancy awakens and breaks free of her restraints. She tears off her mansion's roof and, clothed in a bikini-like arrangement of bed linens, heads to town to avenge herself on her unfaithful husband. Ripping the roof off the local bar, she spots Honey and drops a ceiling beam on her rival, killing her. Harry panics, grabs Deputy Charlie's pistol, and begins shooting, but she picks up Harry and walks away. The gunshots have no apparent effect on her. The sheriff fires a shotgun at her, which causes a nearby power line transformer to blow up, killing her. The doctors find Harry lying dead in her hand.
The film begins by following a tour group at a memorial museum dedicated to Nancy Archer. The patrons are shown a film with Dr. Victor Loeb, who explains that the events surrounding Nancy Archer were true. Nancy was an heiress to her mother's fortune. 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. Even though she knows she will be the town's laughing stock, she also knows what she saw 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. 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), 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, 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.