Geeky 14-year old Ethan is left to babysit his younger sister, Jane, with his best friend Benny but after Ethan inadvertently puts Jane in harm's way, his parents hire a professional babysitter, the beautiful yet mysterious 17-year-old Sarah who, unbeknownst to them, is actually a fledgling vampire.

When Erik Stifler realizes that he's the only Stifler family member who might graduate high school a virgin, he decides to live up to his legacy. After some well-meaning advice from Jim's dad, Erik's ready to take his chances at the annual and infamous Naked Mile race, where his devoted friends and some uninhibited sorority girls will create the most outrageous weekend ever.