Having awoken from their spring break extravaganza at Lake Victoria, the swarm heads upstream where they look to make a meal out of Big Wet, a local water park where when it comes to fun, nobody does it wetter! Though they came to get wet, get loaded and get some, the staff and patrons get more than they bargained for when they must face the fiercest, most bloodthirsty piranhas yet. Lead by the strong-willed, studious Maddy and her friends, Barry and Kyle, the trio must dive in and take on these...

Doctor Baines has been conducting genetic experiments on piranhas and has made them virtually unstoppable. Unfortunately, his assistants, Maggie and Paul, accidentally release the hybrids into the Lost River Lake threatening to destroy everyone in their path. Can they prevent the flesh-eating piranhas from escaping into the ocean and spawning?

Lake Victoria's annual Spring party by 50,000 young revelers is about to turn into a feeding frenzy with prehistoric hunger-pains. With knee-trembler's above the waves and tremors below, released from their dormant sleep, thousands upon thousands of flesh-eating nippers are released into the lake with whetted appetites and razor-sharp teeth. With a motley crew of strangers thrown together to defend these shores, it is now up to them to prevent the largest eat-out in human, and piranha, history.