Dr. Jane Tiptree has withdrawn from public life to conduct sequestered research for the Eunice Corporation. The DARPA is wary of her work with genetically modified chickens but cannot legally interfere in her research. While in transport, one of Tiptree's chickens hatches a reptilian creature which kills the driver and escapes. Meanwhile, near her laboratory in the small town of Climax, Nevada, the populace begin suffering from a mysterious illness with flu-like symptoms.
At a neighboring Eunice-owned quarry, watchman Doc Smith protects excavation equipment from environmentalists. He reports a trespasser, Ann Thrush, but Sheriff Fowler is investigating a series of gruesome killings, perpetrated by Tiptree's missing creature, a Deinonychus. Among the victims is the daughter of Eunice employee Jesse Paloma, but before he raises any suspicion to her research, Tiptree lures him into a laser-protected dinosaur pen where a fully grown Tyrannosaurus rex devours him.
Despite the deaths, Thrush and a group of activists handcuff themselves to excavation equipment in a form of protest. They are encountered by the Deinonychus and everyone except Thrush is slaughtered. Still in shock, Thrush is brought back by Doc to his trailer, where she survives another attack by the creature. Doc discovers a truck with two corpses belonging to Eunice and contacts Tiptree on the vehicle's radio, deducing the creature originated from her facility. As he approaches the lab, Fowler discovers a dinosaur embryo in a carton of eggs and takes it for investigation.
Doc infiltrates Tiptree's laboratory and, at gunpoint, she reveals her experiment subjects to him. The town's mysterious illness is caused by infected chicken eggs, which contain a lethal airborne virus and impregnate women with dinosaur embryos. Her objective is to exterminate the human race, which Tiptree faults as disastrous, and enable dinosaurs to repopulate the Earth. News of the town's deaths reach Eunice sponsors who trace it to Tiptree. In response, the government places the community under quarantine and resolves to kill all civilians — infected or not — on sight.
With the illness rapidly spreading, Fowler responds to a disturbance at a kennel. He confronts the Deinonychus, but both he and the creature suffer fatal wounds in the exchange. Top governmental officials, in a secure underground bunker, also begin plotting the repopulation of the human race in response to the virus; they envision a new social order prograted by strict fertilization policies and artificial wombs. At the laboratory, Doc attempts to escape with a cure to the illness and mistakenly enters the dinosaur pen. Tiptree releases the T. rex which pursues Doc out of the facility. Infected herself, Tiptree births a dinosaur and succumbs to the illness.
Doc returns to Thrush, who has been exposed to the illness. The T. rex enters the quarry where Doc battles the creature using a backhoe loader, impaling and killing the creature with Thrush's assistance. After injecting her with the serum, Doc is killed by government soldiers alerted to his presence, and both his and Thrush's bodies are burned.
After being driven to extinction, great bloodthirsty dinosaurs come back to life with the assistance of a demented genetic scientist. She plans to replace the human race with a super-race of dinosaurs who will not pollute the planet.
