The Quetzalcoatl, along with its offspring, were a small group of giant monsters located in Mexico. The adult Quetzalcoatl could emit a deadly stream of fire from her mouth, fire balls of flames from her mouth, and was covered with a special type of skin that allows her to be uneffected by the most hottest of temperatures.
Quetzalcoatl was discovered in the Southern point of Mexico and at first, only attacked small villages for material in order to build a nest. H.E.A.T goes down to Mexico to investigate and soon meet Lawrence Cohen, the man who originally discovered the giant bird. While traveling up the side of an old ruin, the group is attacked by Quetzalcoatl. Luckily, Monique was able to fend the creature off by making a small eruption come from the ground after firing her gun into one of the pockets of lava. Once again, Quetzalcoatl attacked while the group searched for her. The tranquilizers fired failed to penetrate her body and a new plan of using deadly scorpion poison was thought of.
Quetzalcoatl moved onto attacking another town and began to tear the place to shreds by using her massive talons. Nick fired the poison shot, but missed, and Quetzalcoatl snatched up Elsie in her claws. The creature took Elsie back to her nest where she would act as food for the newborn Quetzalcoatls.
While climbing up the side of the mountain to save Elsie, the group was once again attacked by the Quetzalcoatl. N.I.G.E.L. was sent up to signal Zilla Jr., and just after sending the signal, the robot was destroyed by the bird. Before Quetzalcoatl could kill the team, Zilla Jr. arrived to fight. After saving Elsie from the baby creatures, Cohen and Elsie were saved by the other members of H.E.A.T. Soon afterwards, Zilla rammed Quetzalcoatl into her nest and began using his beam on the rock walls, causing a rock slide. The land beneath the nest began to give way and Quetzalcoatl and her babies were sent into the stream of lava beneath, never to be seen again.