Darren Silverman (Jason Biggs), Wayne Le Fessier (Steve Zahn) and J.D. McNugent (Jack Black) have been best friends since the fifth grade. Now, enter Judith (Amanda Peet), a great-looking but cold-hearted and manipulative psychiatrist who digs her claws into Darren, snatches him from the friendship and breaks up their band.
J.D. and Wayne try everything they can to free Wayne from Judith, including reuniting him wiht his high-school love, Sandy (Amanda Detmer), who is planning to become a nun. Finally, the duo kidnap Judith and fake her death, leaving Darren free to fall for Sandy. Judith doesn't stay "dead", though, and escapes to regain control over Darren. In a last-ditch effort, J.D. and Wayne recruit Neil Diamond, Darren's hero, to break up Darren and Judith's wedding and save Silverman.