They are a couple of anacondas who was captured from the Amazon to be subjected to experimentations. They are held in a Romanian scientific lab funded by industrialist J.D. Murdoch, who wants to produce a serum to cure his cancer. The two snakes are genetically engineered and possess spear tails due to the experiments.
One day, the male anaconda manages to break through his enclosure's wall and kills many people. He then breaks out his mate, and the two snakes escape the lab and go on a rampage. Murdoch sends some mercenaries to recapture the anacondas, but they find out that the female is pregnant. They eventually spot the two anacondas in an old factory and manage to kill the male, however the female gives birth to several babies. Finally, the building is blown up and the snakes are killed, but one of Murdoch's men finds one baby still alive and decides to deliver it to Murdoch.