Justin Long, Matthew Gray Gubler and Jesse McCartney provide the voices for Alvin, Simon and Theodore in this latest instalment of chipmunk adventures. When Dave (Jason Lee) reveals that he is travelling to Miami to propose to his girlfriend Shira (Kimberly Williams-Paisley), the three chipmunks fear for their future, especially as Shira's teenage son Miles (Josh Green) has taken an instant disliking to Dave's furry friends. As the trio put their heads together to try to break up the happy couple, they find an unlikely ally in Miles. With the common ground they share - wanting to break up the engagement - Alvin, Simon, Theodore and Miles do all they can to break up Dave and Shira.