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 for 65 million years. But once they go down, the team discover the ship's alien crew are very much alive... and they have plans for Earth.

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. As the volcano begins to erupt again and Godzilla confronts the bees' queen, the team must find a way to escape the island alive.

When villages in Mexico are attacked by a strange winged creature,ornithologist and Elsie's old fiance Lawrence Cohen calls H.E.A.T. for help. They quickly discover the beast is Quetzalcoatl, an evolutionary hybrid of bird and dinosaur capable of breathing fire and protected by impenetrable feathers. The team must find a way to stop the creature, but matters worsen when Quetzalcoatl takes Elsie to feed its starving young.