When a strange electrical creature known as the Crackler attacks seemingly random locations in Manhattan, the team investigate. But the Crackler isn't behaving like the mutations H.E.A.T. have fought before, and what is its connection to mild-mannered insomniac Sidney Walker?

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.