Description
Adventurer Burt Gummer returns to his hometown of Perfection, Nevada, after a hunt for Shriekers in El Chaco, Argentina. Since the original Graboid attacks, the town's preventative equipment for tracking Graboid activities has fallen into disrepair due to the neglect of native residents Miguel, Nancy Sterngood, and her daughter Mindy. Walter Chang's market has been taken over by his niece Jodi, and the town has gained a new resident, Jack, who creates mock-attack tours for visiting tourists. One afternoon, during one of Jack's tours, his assistant Buford is eaten by an actual Graboid. Jack, Mindy, and Jack's customers manage to escape to warn the town, and Burt determines there are three Graboids in the area.
The residents begin to take action to kill the Graboids, but they are stopped by government agents Charlie Rusk and Frank Statler and a paleontologist, Dr. Andrew Merliss who claim the Graboids are an endangered species, preventing the humans from hunting them. Jack manages to reach an agreement with the agents that if they capture one live Graboid, Burt and the residents will be allowed to kill the remaining two. Burt grudgingly agrees, and he and Jack set out to trap a Graboid while the agents go after another out of their own accord. Melvin Plugg, a fellow survivor from the original attacks, approaches Burt in the hopes of buying his land and developing it into a town. After Burt refuses, a Graboid attacks and swallows him whole. Jack lures the Graboid to Burt's home, having it fatally collide with the underground concrete barriers surrounding the building. He then uses a chainsaw to free Burt from its belly.
Burt, Jack, Jodi, and Miguel later find a badly wounded Merliss; he explains that he and the government agents were ambushed by Shriekers from the Graboid they were chasing, before dying. While tracking the Shriekers, an albino Graboid, later named El Blanco, meaning "The White One" in Spanish—traps them on rocks for the night. After drawing El Blanco away, they find that the Shriekers have molted their skin, becoming winged creatures capable of jet-propelled flight. Miguel is killed by the creature, which then crashes on a metal fence, killing itself. Burt realizes that chemicals in their stomachs react explosively, enabling their flight. Finding them able to carry Graboid eggs, they surmise that they evolved to spread them through flight. Jodi dubs the new species Ass-Blasters. Meanwhile, Nancy and Mindy are attacked by an Ass-Blaster in town and hide in a freezer.
Using a mattress as cover from the Ass-Blasters' infrared vision, the group gets to Burt's house, but are forced to flee when an Ass-Blaster attempts to break in. To keep it from multiplying like its predecessors, Burt rigs his house and his stash of MREs to explode, killing it, however it is only after that they learn from Mindy that Ass-Blasters do not multiply but fall asleep after eating. The group flees to a junkyard, where they build a potato gun from everyday objects to ignite the combustible materials in the Ass-Blasters' stomachs. After they kill four, Burt is attacked by El Blanco and pinned down. Realizing that Burt's ultrasonic watch is repeatedly drawing El Blanco to them, Jack takes it and sticks it to the final Ass-Blaster. El Blanco devours it, saving Burt and Jodi's lives in the process.
In the aftermath, Nancy manages to sell a captive Ass-Blaster, while Jack pursues a romantic relationship with Jodi, depressing Mindy who had a crush on him. Meanwhile, Melvin tries again to approach Burt about selling his land, but Burt informs him that since El Blanco is an endangered species and illegal to hunt, and formed a mutual unspoken friendship with Burt, the residents have decided to take precautions in order to live safely alongside it, thus turning Perfection into a federally protected Graboid reserve and barring Melvin from developing a town. Burt then leaves Melvin standing on a rock with El Blanco circling below.
