In the year 2022, a ruthless prison warden has created the ultimate solution for his most troublesome and violent inmates: Absolom, a secret jungle island where prisoners are abandoned and left to die. But Marine Captain John Robbins, convicted of murdering a commanding officer, is determined to escape the island in order to reveal the truth behind his murderous actions and clear his name.

French nuclear tests irradiate an iguana into a giant monster that viciously attacks freighter ships in the Pacific Ocean. A team of experts, including Niko Tatopoulos, conclude that the oversized reptile is the culprit. Before long, the giant lizard is loose in Manhattan as the US military races to destroy the monster before it reproduces and it's spawn takes over the world.