When Elsie's estranged parents come to New York for her spoiled sister's wedding, she is forced to attend as maid of honour instead of helping H.E.A.T capture a mutated manta ray. When the military's battle with the creature ends up interrupting the wedding, Elsie is determined not only to catch the creature, but to prove to her parents she is not the screw-up they think she is.

Shortly after receiving an anonymous check for $5 million, H.E.A.T. are called toIllinois, where a gigantic mutated chilopod, Megapede, is devouring thousands of dollars worth of crops. The team are unable to stop the creature when they first encounter it, and upon finding it again, they discover it has metamorphosed into a gigantic cicada. The insect's mating call is disrupting all radar in Chicago, and now H.E.A.T must find a way to silence the creature long enough to launch a counterattack.

Just as H.E.A.T has had it with Randy, Elsie convinces the rest of the team to investigate a possible mutation sighting at Area 51, where they discover the real secret of Area 51 is not aliens, but mutations, created by underground nuclear testing. When one of the captive mutations - a mutant thorny devil lizard - breaks out of its cage, the team and Godzilla must stop the creature from escaping the base and destroying nearby Las Vegas.