In the countryside, the boy Alan and his friend Becky steal a creepy wooden box with a powerful voodoo stick inside from his voodooistic neighbor. When the boy draws with the stick, his drunken father is attacked by a snake and vanishes. Years later, Alan and Becky are married to each other; while planting some flowers to celebrate the death of Alan's mother, Becky finds the box buried in the garden and she keeps the stick in her pocket. Meanwhile, five friends are traveling in a monster truck, drinking beer. The driver accidentally runs over Becky, but believes he had hit an animal. When Alan witnesses the hit-and-run and sees his wife dead, he uses the stick seeking revenge against the youngsters.
After an overly ambitious businessman transports an 80-foot python to the United States, the beast escapes and starts to leave behind a trail of human victims. An FBI agent and a snake specialist come up with a plot to combat the creature by pitting it against a bioengineered, 70-foot boa constrictor. It's two great snakes that snake great together!
A team of environmentalists, including a reporter, her camera man, and an environmentalist's famous girlfriend charter a boat and with the captain, sail to a military island. They suspect the island is hosting to illegal activities. Upon arrival, however, they find no one. They finally reach a deserted house, where they find Dr. Susan Richardson, who tells them that everyone on the island is dead, including her father. Richardson's team were working on a compound that could make edible plants grow to super size, however the military intervened with plans of their own. They wanted to test the compound's effects on animals, and proceeded to feed it to several komodo dragons and cobras.
Paleontologist Robert Trenton is called to Northeastern Antarctica near the Indian Ocean to help the FBI build an underground maximum-security military base and prison for the world's most dangerous criminals and terrorists, which is dubbed "New Alcatrax" by the staff. While building the prison, the staff accidentally awaken and unleash a prehistoric Boa Constrictor from its 200 year hibernation.
Mutant snakes survived a terrorist attack on a government laboratory, and they now threaten the town of Santa Mira Springs, California. Seismic activity has brought snakes to the surface, where residents are being bitten. Victims can transmit the virus to healthy persons. The military puts the town under quarantine. Local physicians try to control the epidemic, while the military is primarily concerned with keeping the virus a secret.
A set of vipers has been taken by scientists to mutate them to make a cure for cancer. As their experiment goes awry, the vipers escape into the woods - they're not only biting people, they're actually killing people, in a little town.