A group of tourists is getting ready to enjoy an idyllic vacation at a remote holiday lake. Meanwhile, a mad scientist, obsessed with a military experiment to create mutant piranhas, has accidentally released these carnivorous creatures into the crystal-clear waters. When a group of carefree youngsters decides to jump in for a swim, what should be a fun day in the sun quickly turns into a fight for survival.
As characters begin to disappear at an alarming rate, a small group of brave individuals, including the camp leader and a fearless ex-Marine, embarks on a race against time to uncover the truth about what lurks beneath the surface. With chaos unleashed and the authorities' attention focused on a local fishing event, danger looms over everyone at the shore.
The action scenes escalate as the protagonists try to find a way to stop the piranhas, which know no bounds when it comes to feeding. Amid laughter, scares, and moments of pure adrenaline, the group will discover that there is nothing more terrifying than facing an enemy you cannot see. In an explosive climax, they must fight for their lives as the piranhas, with their sharp and voracious jaws, stalk them at every turn.