Even though Jim (Jason Biggs) and Michelle (Alyson Hannigan) have been dating for several years, she's still surprised when he proposes to her in their favorite restaurant. After she happily agrees, Jim asks his best friends, Kevin (Thomas Ian Nicholas) and Paul (Eddie Kaye Thomas), to help him make sure the wedding goes as smoothly as possible. As the big day approaches, trouble arises when the trio learns their hard-partying friend, Stifler (Seann William Scott), is in town.