Anne is a guest at a luxury resort in the Caribbean when one of her friends sons is killed in a piranha attack. As she starts investigating the attack, they discover this is one of a number of attacks taking place near a nearby shipwreck. At the mortuary, they discover that the cause is a new breed of Piranhas that have wings and can fly, and they show their true viciousness at a beach party.
After special effects work for Roger Corman, who is responsible for the starts of more major careers than any film school, Cameron got his first megaphone gig on this sequel to an early Joe Dante movie, and turned out a soggy dud which shows none of the skills his subsequent monster pictures would demonstrate.
It does feature Henriksen, star of Aliens and The Terminator, and the basic storyline — separated couple come together in the face of underwater menace — served for The Abyss. It plays a lot like a Porky's holiday comedy for the first half, and then the seagoing killer fish learn to fly and big rubber toothy things terrorise the survivors
For curious completists only.