A Manson-like cult leader disappears after freaking out and hacking up a bunch of his followers with a machete. Thirty something years later some kids come and camp out on the site of the killings. Of course, bad stuff happens.

When a crop of doped-up athletes from the Lakecrest College swim team dive into the campus lake to blow off some steam, the bloodsucking leeches below the surface undergo a stunning transformation. After ingesting small amounts of the swimmers' steroid-laced blood, the slimy creatures grow to unusual sizes and set out to sink their teeth into an unsuspecting student population.