Once inseparable pals, Dave (Jason Bateman) and Mitch (Ryan Reynolds) have drifted apart over the years. Dave is an overworked lawyer and family man, while Mitch has thus far avoided most of the normal responsibilities of adulthood. Each is envious of the other's life, and following a drunken binge, the men awake to find they have somehow switched bodies. Dave and Mitch soon discover that things are not as rosy as they seemed and try to find a way to return their lives to normal.