A genetic experiment produces miniature sharks with the voracious appetite of piranhas, which are initially sold as exotic pets before they escape into the water supply of New York City. The creatures begin breeding and attacking people from within the plumbing system, prompting a small group of investigators to race against time to stop the infestation. The film blends low-budget creature-feature horror with a satirical edge as the tiny but deadly predators wreak havoc on an unsuspecting urban population.