Langan plays Lt. Col. Glenn Manning, an officer in the U.S. Army who suffers serious burns to over 90% of his body following an inadvertent exposure to plutonium radiation from a bomb blast. Manning miraculously survives the explosion and his burns completely heal, but the radiation causes him to abnormally grow into a 60-foot-tall giant. At this size, his heart is unable to supply sufficient blood to his brain and he gradually goes insane.
Army doctors attempt to halt and reverse Manning's growth with a formula, but after getting injected with the cure, the colonel grabs the needle and spears one of the doctors with it, killing him on the spot. Manning then escapes from confinement, "kidnaps" his girlfriend, Carol Forrest (played by Cathy Downs), and wreaks havoc in Las Vegas before being cornered by the Army at the Hoover Dam. After releasing Carol he is shot and appears to fall to his death in the Colorado River.