Man has meddled again with mother nature and the result is not only deadly...it's voracious! With a clever screenplay written by John Sayles (Apollo 13) from a story by Richard Robinson, director Joe Dante (Gremlins) creates an eerie and devilishly fun tale of mutant piranha terrorizing a local swimming hole. On an inviting tranquil evening, two venturesome teenagers take a moonlit skinny-dip in the inviting waters of Lost River Lake...little did they know they would quickly become fish food for a hungry school of man-eating piranha!

Their deaths prompt an investigation that reveals a governmental cover-up of a top secret experiment called Operation Razorteeth. And it only gets worse. These insatiable, gilled monsters are heading downstream where a newly opened swimming resort will give them a smorgasbord of tasty vacationers, unless a brave outdoorsman (Bradford Dillman) and a sharp, beautiful investigator (Heather Menzies) can stop their deadly spawn...for good.