Lt. Col. Glenn Manning (Glenn Langan) leads a desperate rescue as a test explosion of the first atomic plutonium bomb at a remote Desert Rock, Nevada site goes awry. When an unidentified civilian aircraft crashes near the detonation zone, Manning rushes in to pull the pilot to safety. The blast hits him, and he is left badly burned. He survives the encounter, but the event triggers a terrifying transformation.
He is rushed to the care of specialists, including Dr. Paul Linstrom (William Hudson) and military scientist Dr. Eric Coulter (Larry Thor). The prognosis is grim. Linstrom does not tell Manning’s fiancé, Carol Forrest (Cathy Downs), that Glenn’s chances of survival are slim. The next day, Glenn’s burns begin to heal in an extraordinary way, defying medical expectations, which only deepens the mystery surrounding his condition. Carol, barred from visiting him for the moment, learns that Glenn has been moved to a rehabilitation and research center in Summit, Nevada.
Upon entering his room at Summit, Carol is shocked to discover the extraordinary truth: Glenn has grown into a giant. The revelation is not just a flash of fear but a profound transformation that changes everything about their relationship and the world around them. The medical team explains that the plutonium exposure accelerated his body’s cellular growth, far beyond any normal human limits. Yet there is uncertainty about whether they can slow or stop the process, and they fear Glenn’s strength and sanity could deteriorate as he continues to grow.
As the days pass, Glenn’s size increases dramatically. What began as a 16-foot rise becomes a terrifying 22-foot advance, leaving him isolated and struggling with anger, loneliness, and sorrow. Linstrom and Coulter reveal a troubling fact: Glenn’s heart is growing at only half the rate of his body, a mismatch that will eventually overwhelm his circulatory system and end in a catastrophic failure. The doctors warn Carol that his mind may fracture long before his heart gives out, a danger that makes any contact with him precarious. Despite Carol’s efforts to reach out and console him, Glenn’s mood darkens, and he lashes out, ordering her to leave him alone.
News of the “giant man” spreads, and a vast manhunt begins as the military searches for the now enormous figure. By the time Glenn reaches about 50 feet, he is a bewildered, angry behemoth, and the world watches with a mix of fear and awe. He climbs toward the Las Vegas Strip, drawn by a sense of confusion and a desire to understand the world that has grown so large around him. The giant’s rampage through casinos and streets culminates in a direct confrontation with law enforcement, as helicopters and troops close in on him.
The chase leads to a dramatic confrontation at Boulder Dam, where the military and scientists finally attempt to intervene. Linstrom uses a bullhorn in a bid to reach Glenn, while Coulter and Linstrom prepare a special syringe carrying a serum designed to halt his growth. They approach with caution, hoping to inject him and buy him a chance at a normal life. In a tense moment, Glenn accepts the attempt and the syringe is plunged into his ankle. The act does not go smoothly; in a fleeting instant of anger, he tears the syringe away and savagely strikes Coulter, killing him.
With the serum in place, Glenn’s behavior becomes vulnerable and uncertain. He grips Carol and moves toward the dam, where the soldiers are waiting to fire if necessary. Carol, pleading with him to calm down, helps him understand what he is risking by continuing to grow. In a climactic turn, the ailing giant is coaxed into releasing her, and the soldiers proceed to open fire in a last-ditch effort to prevent further danger. The confrontation ends with Glenn slipping and plummeting into the Colorado River, appearing to meet his end when the waters claim him.
The film closes on a somber note: a man who survived a catastrophic blast becomes a warning about the cost of unchecked power and the fragility of the human body under extraordinary circumstances. The story sits at the crossroads of science fiction and tragedy, highlighting the ethical dilemmas of experimentation, the loneliness that can come with monumental change, and the relentless pursuit of a world where limits can be shattered—and sometimes, shattered beings must confront the consequences.
