When an earthquake strikes Mexico and creates a brand new volcano overnight, two geologists are sent to study the phenomenon. Once they arrive at the village of San Lorenzo, the townsfolk tell the men of unexplained disappearances, livestock deaths and strange roars that have been happening in their village, suspecting a demon bull is to blame. (Richard Terry wishes he'd thought of that.)

But when the volcano erupts again, the true cause of the mysteries is revealed to be giant, prehistoric scorpions! In typical movie scientist fashion, the geologists team up with the Mexican army to destroy the prehistoric arachnids.

Joel, Servo and Crow add a specimen to their riffed bug collection with The Black Scorpion!