When people start showing up with bite marks on their necks, Ty and Abby can't help but wonder if maybe vampires aren't a myth after all. But when they dig a little deeper, they discover that it's another kind of blood sucker that's causing trouble - leeches! Worse, these hungry invertebrates are led by 869, a giant mutated talking leech that's had enough of his kind being trapped in hospitals under harsh florescent lights. He only has one goal: freedom for leechkind!