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.

Captain Etienne Navarre is a man on whose shoulders lies a cruel curse. Punished for loving each other, Navarre must become a wolf by night whilst his lover, Lady Isabeau, takes the form of a hawk by day. Together, with the thief Philippe Gaston, they must try to overthrow the corrupt Bishop and in doing so break the spell.