Through a series of misunderstandings, Alvin, Simon and Theodore come to believe that Dave is going to propose to his new girlfriend in New York City - and dump them. They have three days to get to him and stop the proposal.Wikipedia
Alvin and the Chipmunks: The Road Chip Reviews
There is very little heart to all the mad rush in the movie. You are moved when Dave adopts the chipmunks legally or when Miles starts looking at them as family and not foes. Frankly Miles' change of heart was a little out of the blue, but it fits just fine for the age group it is catering to.
It's a silly story and the drama is terribly stretched and worn to bits. There's no comedic relief to be had and the musical experience which starts off as peppy ends up becoming tedious and boring.
It's all mostly harmless as far as these things go - lazy, sure, but harmless.And if you ever wanted to see a chipmunk sing Baby Got Back and Uptown Funk, well, congratulations, Christmas is here.