Russ Duritz (Bruce Willis) is a powerful businessman, self-absorbed and immersed in work. By the magic of the moon, Russ one day meets Rusty (Spencer Breslin), a chubby, charming 8-year-old version of himself who can't believe he could turn out so badly -- with no life and no dog. With Rusty's help, Russ is able to reconcile the person he used to dream of being with the man he's actually become in director Jon Turteltaub's wry family comedy.