This spin-off of the Tremor movies chronicles the town of Perfection, Nevada, which has a little problem with great big worms. The Graboids, and their offspring the Shriekers and Ass-Blasters, have overrun the valley but are on the government's protected species list. The locals are (barely) allowed to live there rather then leave their homes, as long as they don't harm the creatures, particularly the giant Graboid known as "El Blanco." Complicating matters, a secret government lab accidentally unleashed a gene-blending substance called "Mixmaster" into the area, occasionally causing various animal-types to recombine into new monsters.
The natives of Perfection include survivalist Burt Gummer, 60's hippy-type Nancy Sterngood, and grocery store owner Jodi Chang who all try to make a living. New to Perfection is tour guide Tyler Reed and Rosalita Sanchez, a mysterious woman with a past. Government representative W.D. Twitchell keeps an eye on the whole situation.