Valentine "Val" McKee and Earl Bassett work as handymen in Perfection, Nevada, an isolated ex-mining settlement in the high desert east of the Sierra Nevada mountains. When they eventually tire of their jobs and choose to leave, they find the earth infested with gigantic man-eating wormlike creatures that live below and the slightest vibration of the ground can endanger their very lives.
A man on an oil field in Chiapas, Mexico flees from an underground creature which emerges and eats the man, revealing it to be a graboid. Years after the events of Tremors (film), Val McKee has moved away and married Rhonda LeBeck, while Earl Basset has squandered his fortune on a failing ostrich ranch. He is approached by Carlos Ortega, who informs him that graboids are killing his workers at his oil field in Sonora, Mexico, and hires him to hunt them down. Earl initially declines, but Ortega's taxi driver, Grady Hoover, convinces Earl to change his mind; both join the hunt. Upon arrival in Sonora, Earl learns that the company would pay him double if he caught one of the creatures alive. He also meets geologist Kate Reilly and her assistant Julio, who are scientifically investigating the Graboids.
The now famous Burt Gummer returns to his hometown of Perfection, Nevada for the first time in years, but the deadliest Graboid evolution yet forces him to save the town he swore to protect.
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.
In 1889, seventeen men die under mysterious circumstances, and spooked by recent events, the miners who populate the town leave in droves until there's nothing left but a shell of a community.
Burt Gummer, now a star in his own survivalist series, and his new cameraman, Travis Welker, are approached by South African Wildlife Ministry agents Erick Van Wyk and Johan Dreyer, who hire them to deal with Graboid#Ass-Blaster in South Africa.
Burt Gummer suspects that giant worms are being utilized as weapons at a research facility in Canada. He soon finds himself in a race against time to create an antidote from one of the creature's venom to save his own life.
When a group of hunters genetically modify Graboid eggs, they face an all-out war against the larger, terrifyingly intelligent Graboids, and the swiftly multiplying Shriekers.
