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.

The Chipmunks believe that Dave plans to propose to his new girlfriend in Miami.--and dump them. They have three days to get to him and save themselves not only from losing Dave but also from gaining a terrible stepbrother.

The world-famous singing preteen chipmunk trio return to contend with the pressures of school, celebrity, and a rival female music group known as The Chipettes.