After a group of college friends get together for a murder mystery weekend, the fun and games take a turn for the worse when some of them end up disappearing.

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.