Area 51

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.