Shriekers are spotted in Juniper, Arizona and Twitchell sends Burt and Tyler to handle the situation. However, the Fish and Wildlife Service are also in town and manage to kill five Shriekers. They also take one alive for study and when it gets a hold of some food, the Shriekers start to multiply again. Now Burt and Tyler have to stop them from massacring the entire town.
Residents of Perfection are facing money troubles and Rosalita decides to take a job at Melvin's latest business venture, the Oasis. But some of the water Melvin uses for the Oasis' lagoon actually came from Perfection and contains Mixmaster, creating a deadly six foot shrimp. And when Melvin's attempt to kill it drives the shrimp out of the lagoon, Tyler and the others will have to stop it before it escapes into the wild.
Two Las Vegas criminals named Max and Frank have to lay low before their next crime. With time on their hands, they go to Perfection to settle a disagreement about the existence of Graboids. They soon enough encounter El Blanco, which kills Max and also eats the key needed for their crime. And the only way to get it back is to kill El Blanco.
Burt finds and kills a Shrieker in the valley, only to learn it was a part of a government funded project to train Shriekers for rescue missions. But when a storm knocks out the equipment controlling them, the remaining Shriekers escape and multiply. Now to survive, the Perfection residents must make a stand at Burt's place.
Burt rescues newcomer Tyler Reed from the government-protected Graboid known as El Blanco. It happens that Tyler is the new owner of Perfection's tourist business and he couldn't have come at a worse time. El Blanco is becoming more aggressive and the Perfection residents have to figure out why before they become the next meal.