Professor Gerald Collins returns to Collinwood from an archaeological expedition to Mexico with several crates of animals -- giant rats, poisonous snakes and rare lizards. His daughter, Irma, turns to Barnabas for help. She fears her father also brought back a Quetzalcoatl, the terrible, cursed feathered serpent of Aztec legend. Irma, with the help of Barnabas, tries desperately to clear her father's name, and in doing so, stumbles upon a monster even more dreadful than the Quetzalcoatl.