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.

Suddenly, a mysterious murderer strikes at Collinwood, and a feathered serpent is reported flying over the area. The townspeople, already angered by the presence of Barnabas at Collinwood, now demand that Professor Collins turn his specimens over to a zoo before anyone else is killed.

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 Quetzacoatl.