A mutant giant rat emerges from the sewers of Manhattan.

When a strange electrical creature known as the Crackler attacks seemingly random locations in Manhattan, the team investigate.

The team are called to help a rescue mission for xenobiologist Alexander Preloran, who disappeared while on a mission to explore the Leviathan, an alien spacecraft buried at the bottom of the Pacific Ocean for 65 million years.

H.E.A.T. investigates the tropical island of Santa Marta in the wake of a devastating volcanic eruption. But what they find on the island is that, due to irradiated lava, a hideously mutated ecosystem has developed, including carnivorous plants and gigantic bees.

When villages in Mexico are attacked by a strange winged creature, ornithologist and Elsie's old fiancé Lawrence Cohen calls H.E.A.T. for help.

H.E.A.T. heads for Scotland after Dr. Hugh Trevor of the Pisces Marine Research Institute claims his facility was attacked by the Loch Ness Monster.

As tension threatens to break up the H.E.A.T. team for good, major problems arise: a Giant Bat is terrorizing the countryside of Nigeria, the U.S. military has dredged the Leviathan ship from the bottom of the Pacific, and worst of all, the aliens are back.

From their secret base on Isle del Diablo, the aliens assemble their forces; H.E.A.T. desperately fights to resist.

As the aliens and their mutation allies attack Earth, H.E.A.T. escapes captivity. They battle to defeat the alien onslaught and free the mutations from their control to help humanity fight back and save the planet from conquest.

A trip to Japan to investigate a number of mysterious disappearances leads to a battle of wills between H.E.A.T. and the Japanese military, who perceive Godzilla to be a threat.

H.E.A.T. are dispatched to aid investigation into the disappearance of a search party looking for oil in Antarctica.

Godzilla is throwing infantile tantrums and H.E.A.T. are growing worried about their ability to control him.

H.E.A.T. is charged by the Pentagon to investigate the growing population of spiders near an Army base in the Canary Islands.

When Godzilla is accused of attacking New York, the military call in H.E.A.T. to help contain him. But Phillipe Roache has returned from France...with orders to terminate Godzilla.

The Techno-Sentient, an alien piece of technology, falls to Earth and begins to bond with all manner of human technology, growing to gargantuan proportions.

Acting on confidential information from Phillipe, H.E.A.T. investigate an abandoned lab in the Amazon rain forest where, 50 years before, French scientists succeeded in creating a creature made of pure DNA.

While Craven is laid up sick back at H.E.A.T. headquarters, Nick, Randy, Elsie and Monique assist Godzilla in a battle with a Mutant Jellyfish. The Heat-Seeker is engulfed by a mysterious storm which propels the team into a bleak, post-apocalyptic future where Godzilla is dead and the world is dominated by genetically engineered, 5-legged mutations known as Dragmas.

Shady promoter Maximillian Spiel entertains wealthy ticket holders with a series of “cage matches” between giant mutations like the Shrewster and the Giant Centipede. For his next bout, Spiel sets his sights on the “ultimate monster”… Godzilla.

In Miami, Godzilla, H.E.A.T., and Major Hicks battle Skeetera, a mutated bloodsucking mosquito-like insect who adapts the powers of the creatures she feeds on. As they attempt to contain the creature they are interrupted by the mutation rights fringe group known as S.C.A.L.E. (Servants of Creatures Arriving Late to Earth).

On the Arabian Peninsula, a team of archeologists led by Professor Abrim Kasam unearth an ancient statue of the flying lion Norzzug, the guardian of the ancient city of Amon-Ra. When restoration specialists spray the statue with an anti-oxidant solution, the iron-skinned creature suddenly comes to life.

A traveling carnival arrives at Madison Square Garden, and it's run by a crooked ringmaster known as Theodore P. Bunkum, who specializes in putting various captured mutations on display for public amusement. Bunkum places a hefty bounty on Godzilla, determined to add this most famous mutation to his carnival side show, and this incites H.E.A.T. to attend one of his shows, where they are quickly appalled by his treatment of the various mutations featured in it.

While on a romantic cruise in Alaska, Nick and Audrey’s ship is attacked by a Giant Turtle.

A new and deadly mutation, a plant-like creature known as Bacillus (who may have been inspired by Biollante), appears and begins wreaking havoc, prompting H.E.A.T. to call upon Godzilla. During the battle, Godzilla is seriously injured and rendered catatonic as the result of being injected with a highly dangerous form of mutated bacteria by Bacillus. In order to save their kaiju ally, Tatopoulos and Monique travel within Godzilla's body in order to carefully exterminate all of the mutant bacterium. Now fully healed, Godzilla attacks Bacillus anew, and eradicates the creature with his incendiary breath.

Elsie is suffering from a family problem of a personal nature, along the lines of sibling rivalry: her sister's wedding is soon to take place, and she is chagrined due to the disproportionate amount of attention and familial adoration that her sister has received in contrast to her. Further, she feels that her family has little respect for her choosen vocation, i.e., her activities with H.E.A.T. [that must be quite a hard family indeed to show a lack of appreciation for a daughter who has routinely risked life and limb for her planet by investigating and battling dangerous, life threatening giant monsters, and even helping to thwart an alien invasion! Her sister must truly be the world's most talented ass-kisser].

H.E.A.T. investigates a gigantic caterpillar-like mutation known as the Megapede, who is rampaging through the neighbor states of Illinois and Indiana. Godzilla is called upon to render assistance, but the Megapede sprays a form of poisonous foam, and also has poison producing spurs along its many legs, both of which serve to keep the Kaiju King at bay. The mega-insect finally climbs atop a building, forms a cocoon, and transforms into a huge winged insectoid creature with the habit of disrupting radar frequencies by rubbing its wings together, thus wreaking much havoc. H.E.A.T. concocts a poison neutralizing foam, which it spreads on the kaiju's wings, allowing Godzilla to attack and defeat the creature more easily.