At a military site in
Desert Rock, Nevada, a test explosion of the first atomic
plutonium bomb does not detonate as expected. When an unidentified civilian aircraft crash lands near the site, Lt. Colonel Glenn Manning runs into the detonation area to rescue the pilot. Once in the detonation area, the bomb goes off, and Glenn gets caught in the radioactive blast. Surviving the blast but suffering from
third-degree burns over almost his whole body, Glenn is treated by specialist Dr. Paul Linstrom and military scientist Dr. Eric Coulter. Glenn's fiancée, Carol Forrest, anxiously awaits a
prognosis, but Linstrom refrains from telling her that Glenn is extremely unlikely to survive. The following day, Linstrom and Coulter are stunned to discover that Glenn's burns have completely healed. That evening, Carol is not allowed to see him and learns the military moved Glenn to an army rehabilitation and research center in Summit, Nevada. She drives there and gets admitted entry. Upon entering his room, Carol faints in horror as Glenn has mutated into a giant about 16 feet tall. The next day, Linstrom tells Carol that Glenn's exposure to the plutonium blast caused his body's cells to multiply at an accelerated rate, resulting in his abnormal growth. Linstrom admits that he and Coulter do not know if they can stop it and that if they do not, Glenn will keep growing until he dies. Awakening the day after, Glenn is initially frightened, then greatly disturbed. Carol sees him the following day to comfort him, but Glenn is now roughly 22 feet tall, distant, and depressed. While the public knows he survived the explosion, the military has kept the truth of his condition secret. advertisement from 1957 for
The Amazing Colossal Man and co-feature,
Cat Girl. As Glenn reaches 30 feet tall, Linstrom recommends that Carol spend time with him. Despite her encouragement, Glenn is angry and bitter. Linstrom reveals that Glenn's heart is growing at only half the rate of his body, and soon it will not be able to support his enormous size and weight. He warns Carol that Glenn's sanity will decline before his heart finally explodes. That night, Carol tries to console Glenn, but he loses his temper and shouts at Carol to leave him alone. The following morning, Glenn disappears as Coulter reports to Linstrom that he may have found a solution to Glenn's growth. Led by Colonel Hallock, the military conducts a 10-mile-wide search for the now 50-foot-tall Glenn, but with no results. When Carol asks Linstrom if she can help in their search, he cautions Carol that Glenn may no longer recognize her. Coulter reveals that he has created a special
syringe filled with a serum that will stop his growth. Meanwhile, the local news relays that a "giant man" was spotted approaching Las Vegas. As the military heads there, Glenn, now over 60 feet tall and confused, is drawn to the
Vegas Strip. He wreaks havoc on various casinos. When his behavior alarms the police, they begin firing at Glenn, enraging him. He destroys the
Pioneer Club's
Vegas Vic sign, then heads toward
Hoover Dam as army helicopters track his movements. Linstrom, Carol, and Coulter attempt to intercept Hallock's troops. After landing at the dam, Lindstrom uses a bullhorn to try reasoning with Glenn, who seems to listen. Coulter and Linstrom take the enormous syringe and plunge it into Glenn's ankle. He removes it and angrily spears Coulter with it, killing him. Then Glenn grabs Carol and starts across the dam. Linstrom stops Hallock from attacking prematurely before he and Carol implore Glenn to release her. Though Glenn is disoriented, he complies. Once she's free, Hallock orders his men to open fire, causing Glenn to tumble into the
Colorado River to his apparent death. ==Cast==