While in New Orleans covering Mardi Gras, Audrey hears rumours of a strange 'Swamp Beast' and decides to call in H.E.A.T.. The creature swiftly proves itself a match for Godzilla, and the team begin to suspect something is afoot when the locals claim the beast is the swamp's revenge against corrupt local politician, Paul Dimanche, who wants to mine oil in the bayou. But can they prove it before the Swamp Beast destroys New Orleans?

The Deep-Dweller, a huge mutated frog fish, begins to attack boats and fishing ships off the coast of New Jersey. H.E.A.T. must help Godzilla drive the creature back to deeper waters, and also deal with the interference of the sleazy and obnoxious tour promoter Milo Sanders, who hopes to make money by getting good footage of Godzilla.