When Lt. Col. Glenn Manning is exposed to radiation during a nuclear testing accident, he begins growing in size. As he continues to grow, he becomes increasingly volatile and destructive, causing chaos in Las Vegas and other cities. Eventually, he becomes a giant towering over the city skyline, leading to a final showdown with military forces.

After being exposed to radiation, a man grows into a giant with a disfigured face and goes on a rampage in Los Angeles. The authorities try to stop him, but their efforts are hindered by bureaucratic inaction and the monster's own tragic past.