Burt is called to take care of graboid trouble in Mexico. Two Mexicans find a split open graboid after their truck breaks down. They find the radio station torn to pieces and walking creatures attack them. They kill one and take off in a van. The girl at the town is attack by one and the Mexicans kill it. Burt arrives, out of ammo, and with a live Shrieker. They discover Shriekers heat-seek and reproduce by eating. A Shrieker that hitched a ride on Burt's truck and eats. Soon the town is overrun with Shriekers.