Paul Diller is the brains behind a multi-million dollar jewel heist. The team includes Robert Lasky, and his girlfriend, Kate Neville. After they steal the gems, they hurl them to the bottom of Brazil's deepest lake. Diller then fills the lake with deadly man-eating piranhas. When two of the thieves try to recover the riches for themselves, one meets a violent and bloody death. The other confronts Lasky, who denies knowledge of the incident. He is busy pursuing a beautiful model named Gabrielle. Diller uses Gabrielle as a way to separate Kate from Lasky. He admits to Kate that he had planted the fish, and that they have now multiplied beyond his wildest dreams. The plot takes twists and turns, deep-diving through bloody caldrons of violence. Who can make it through the flesh tearing jaws of the killer fish?