Archaeologists in egypt accidentally reawaken Norrzug the Iron Lion, a gargantuan sphinx-like monster that once served as the guardian of the ancient city of Amon-Ra. H.E.A.T. discover from ancient texts that the people of the city deliberately rusted the creature to stop its rampage after it turned on them. Now the team must find a way to repeat the feat before this mythological terror devours every last drop of oil in the Middle East.

When circus master Tobias Wilson brings his 'Mutant Mania' circus to Manhattan, things go badly wrong when a mutated sea anemone, called Medusa, escapes her tank and goes on the rampage. When the team discover the creature is sucking water out of her victims, as she needs the electrolytes found in water to survive, the race is on to stop Medusa before she drinks every drop of water on the planet.

While on a romantic cruise to Alaska, Nick and Audrey's ship is attacked by a mutated turtle, but they are saved - not by Godzilla, but by Komodithrax, a mutated Komodo dragon. When Godzilla heads for Alaska to find Nick and H.E.A.T. follow, they make a shocking discovery: Godzilla and Komodithrax are in love, and Godzilla has become surrogate father to an egg laid by Komodithrax. But with the menacing turtle still nearby, and the U.S. military ordered to destroy all monsters in the area, can Nick and the team protect the two gargantuan reptilian lovers?