Playing around while aboard a cruise ship, the Chipmunks and Chipettes accidentally go overboard and end up marooned in a tropical paradise. They discover their new turf is not as deserted as it seems.

Alvin, Simon and Theodore are back, along with their stressed-out manager, Dave. But this time they've got competition: The Chipettes.

After being home-schooled abroad, new student Cady gets a crash course in high school life when a popular clique of girls invites her to sit with them.