Nancy Archer, Daryl Hannah, inherits her mother's estate, a windfall that stirs ambition and unease in their desert town. Nancy's father, Hamilton Cobb, William Windom, hopes to use the money to gain control over the town's businesses and influence. Meanwhile, Nancy grapples with low self-esteem and a troubled marriage to Harry Archer, who keeps a mistress, Honey Parker, Cristi Conaway, and is eager to seize the family fortune for himself.
One night, Nancy glimpses a UFO in the desert, a gleaming beacon that refuses to fade from her memory. She keeps the sighting secret, fearing ridicule from those around her. Eventually she convinces Harry to accompany her on a second, closed-door desert drive, hoping to share what she saw. The UFO descends, its light enveloping the car, and when Nancy steps outside for a closer look, a powerful beam traps her and the craft drifts away with her aboard. Harry quietly returns to town and does not report the kidnapping, leaving Sheriff Denby and Deputy Charlotte Spooner to piece together what happened.
A dazed Nancy is later found atop Honey's salon and is brought home. Hamilton grows suspicious that Harry left her out in the desert, while Harry denies any foul play. A heated argument between the two men ends with Nancy losing her temper, and—much to everyone's astonishment—she begins to grow. Her clothes tear as she expands, and her head breaches the attic ceiling, signaling the start of a dramatic, irreversible transformation.
Nancy is moved to a large stable, where she meets Dr. Loeb, an expert brought in to understand what is happening to her body. Paul Benedict portrays the physician, who notes a hormonal surge accompanying Nancy's rapid growth. He explains that the condition is unique and precarious, and that attempting a conventional, controlled environment for therapy could be dangerously destabilizing for her heart. Nancy begs for a cure, but the doctor warns that her situation is not easily managed and that any exertion or stress could prove lethal. This grim reality feeds Harry’s growing fear about losing the family business, and he begins to see a dark path to secure his own future.
As Nancy gains confidence and strength, she becomes more defiant and resourceful, even inviting Harry to dinner to discuss their evolving dynamic and her new perspective. During the confrontation, Harry reveals his affair with Honey and, under the guise of normal disagreement, he insults Nancy just enough to trigger a severe reaction. She faints and crashes into the stable, prompting her escape into the town. Nancy searches for Harry, determined to confront him and seal her own fate.
In a desperate bid to regain control, Nancy captures Honey but spares her, urging her not to act foolishly. She then tracks down Harry and flees into the desert, with National Guard helicopters on their tails. A tense sequence of danger follows as they attempt to outrun the pursuit, culminating at high-voltage power lines that threaten to end Nancy’s ascent for good. Hamilton and the authorities close in, and Nancy seizes the moment to reveal her plan: she intends to use her wealth to reshape the town’s future and deny Harry the power he sought.
Tragedy strikes when a miscommunication from Sheriff Denby leads to a sniper shot that hits Nancy. She falls onto the power lines, but is rescued and carried away—still clutched to Harry—by a hovering UFO, which confirms that her extraordinary claims were real. The crowds disperse in a mix of relief and awe, while Honey and Hamilton strike a new business arrangement that shifts the town’s balance of power.
Inside the UFO, Harry undergoes a surreal therapy session under a tiny dome, watched by Nancy and two other giant figures as the craft lifts into the night. The town memories begin to shift as the ship departs, leaving behind a symbol of Nancy’s remarkable journey. A memorial museum dedicated to Nancy Archer is later established, honoring a woman who transformed herself and the fate of the town.
