The episode opens with a man discovering a Mayan step pyramid. He goes inside and uses his palm to open a door with a paw-like marking on it. When the door opens, he sees a narrow pathway to a bird-shaped altar with a similar marking. He tries to open it, but he is rejected and the room begins to fill with smoke. When the man gets outside, he is attacked by the Quetzalcoatl. The opening credits roll, and the show cuts to Zilla Junior playing with a fishing net at H.E.A.T. headquarters. Inside, Monique Dupre and Elsie Chapman watch a news report on TV, that details the destruction of several small Mexican villages. They receive a phone call, which prompts them to take a trip to the destroyed Mexican villages, where no one wants to talk to Nick Tatopoulos about the damage. Monique asks where Elsie's colleague who called them on the phone is, and he appears shortly after. The man (named Lawrence Cohen) takes them to the temple he had unsealed at the beginning of the episode and tells them about Quetzalcoatl. the group is skeptical, until Randy Hernandez discovers a large feather, and the bird actually appears. Monique and Nick are able to fight it off, and later that night Elsie and Lawrence discover that the Quetzalcoatl is covered in scales instead of feathers. They then share their findings with Nick, who observes that the scale has a silicate coating and questions if the kaiju is a silicon based life form. It turns out that it is not, but its scales are coated so that it can live inside of volcanoes. It attacks them, but not even five Rhino tranquilizers could not bring it down. It is then decided to use black scorpion venom against it, but they only have enough for one shot. Quetzalcoatl begins to attack a nearby village, and Elsie is taken by it. The rest of H.E.A.T. and Lawrence theorize that Quetzalcoatl or "Q" may have a nest that it is taking food to. The group finds Elsie in the nest with the help of N.I.G.E.L., and they signal Zilla Junior to aid them. Lawrence enters the nest to save Elsie, and the two are lifted out by H.E.A.T.. Zilla Junior is able to defeat the Quetzalcoatl, and it and its young are re-sealed in the volcano. Lawrence then tries to re-acquaint himself with Elsie, but he becomes distracted by his work again.
The Quetzalcoatl is similar to the Antimatter Space Buzzard from the movie The Giant Claw. Its young are reminiscent of the Velociraptors from Jurassic Park.
Randy mentions that the volcano "has a rumbly in its tumbly", a reference to Winnie the Pooh.
The episode mentions that the bird's feathers are actually scales, which is odd given that dinosaurs possessed feathers and the scales on bird feet are theorized to be modified from scales. While the episode also states that its scales contain silicon (i.e. differentiating it from anything real), it should be noted that the idea that dinosaurs might be feathered started to take root in 1983, well before the show aired.
It is also mentioned that birds are descended from dinosaurs, which is not strictly true, rather birds are considered a class of dinosaur, most closely related to the maniraptoran theropods (such as the famous Velociraptor).
At 14:41, Nick's hair disappears for a second. While it appears that it was erased, this is presumably due to layer issues.