The film starts with a newscast about a year after the attack on Lake Victoria by prehistoric piranhas, an eradication campaign has left the lake uninhabitable by life, and the town itself has been largely abandoned as a result of the drying-up of their main revenue source, tourism. The beaches have dried up and there is no longer Piranha in the lake. No explanation is given about the fates of the original survivors.
At a nearby lake, Clayton (Gary Busey) and Mo walk into the water to recover the body of a dead cow. The viewer finds out that eggs have been laid inside the cow and the metabolism is forcing the eggs to come out via farting from its rear end. Oblivious to the danger, the Piranha bite and swarm onto the two farmers. Mo is completely devoured and disappears under the water leaving his hat bobbing into the crimson of his blood. Clayton makes one more bid for freedom, jumping out of the water. Alas he doesn't make it far and in one last bid to show the Piranha that he can't be beaten, he pulls one off his face and bite it's head off. He then spits it out towards the camera as the other Piranha rip him to shreds under the water........