When an army of Graboids - giant, carnivorous underground worms - threaten the Petromaya oil refinery in Mexico, its owners call on Earl Bassett, who once helped kill four of the creatures in Perfection, Nevada. Having squandered the money that came from his resulting celebrity status, Earl is convinced by the $50,000-a-head bounty offered, as well as the enthusiasm of admirer Grady Hoover, who becomes his partner. At Petromaya, Earl and Grady meet geologist Kate Reilly, and begin Graboid...