In a desperate search for her missing brother, Joyce Manning travels to Mexico after learning about mysterious reports of a giant being sighted in the region. Her brother, Glenn Manning, a former soldier who was exposed to an accidental radiation blast, had grown to an enormous size before disappearing. Upon reaching Mexico, Joyce encounters Dr. Carl Noymann and Major Mark Baird, who are skeptical at first but soon realize the giant is indeed Glenn. The giant Glenn has become disfigured and mentally unstable due to his ordeal, making him a rampaging and tormented creature rather than a coherent person.

Determined to capture him alive and bring him back to the United States for medical treatment and containment, they devise a plan to subdue the colossal beast. Despite numerous challenges and the overwhelming power of the creature, they manage to sedate him and transport him back to an American military base. There, they desperately seek a way to help him while managing the constant threat he poses due to his uncontrollable behavior and massive strength. Tensions rise as the team grapples with ethical dilemmas and scientific obstacles, caught between their desire to save Glenn and the immediate danger he represents to everyone around him.