A scuba diving instructor, her biochemist boyfriend, and her police chief ex-husband try to link a series of bizarre deaths to a mutant strain of piranha fish whose lair is a sunken freighter ship off a Caribbean island resort.

In Piranha II: The Spawning, a Caribbean island is plagued by killer fish that attack anyone in their path. As the terror escalates, a group of people must find a way to stop the bloodshed and save themselves.

When a pair of missing hikers are found dead in the river, it's discovered that mutant piranhas, created as an experiment by the US Army, have been released into the water. The piranhas wreak havoc on a nearby summer camp, putting everyone's lives in danger. A group of survivors must race against time to stop the deadly fish before it's too late.