Dave Seville (Jason Lee), the Chipmunks (Justin Long, Matthew Gray Gubler, Jesse McCartney) and the Chipettes are taking a luxury cruise to the International Music Awards. Of course, Alvin cannot resist the urge to create havoc, and the singing rodents soon find themselves marooned on a seemingly deserted island. While Dave and an unlikely ally launch a search, Alvin and company discover that they are not alone on the island, as they first thought.