Piranha

Two teenagers on a date decide to visit an abandoned military compound and go skinny dipping in the swimming pool. Unknown to them, the military base is home to a secret government laboratory in which scientists are performing dangerous experiments and creating a variety of mutated creatures. Suddenly the two teenagers are eaten alive by carnivorous piranhas.

The case of the missing teenagers attracts the attention of an insurance investigator, Maggie, who decides to go Lost River Lake with a local guide, Paul, in order to find them. They come across the military base and Maggie thinks to look inside the swimming pool to see if the bodies of the two youths are inside. Although one of the scientists desperately tries to stop her, she drains the pool and accidentally releases the deadly piranhas into Lost River Lake and the ocean.

Maggie and Paul try to warn everyone about this new danger infecting the waters, but the US army will do anything to keep the mess a secret.