It's an all out brawl this Valentine's Day at Clyde C. Crashcup Elementary, but who's to blame now? Of course, Alvin for always pulling pranks on Brittany ever Valentine's Day during their dates, Brittany for finally turning him down after learning her lesson, and also a surprise transfer student who can't help but make everything between the two love birds much, much worse off!

Tensions arise and the natural balance begins to crumble as Brittany Miller, the lead singer of the "world famous" trio "The Chipettes" and self proclaimed "most popular" girl is UPSTAGED by her quieter and very shy sister Jeanette after a trick by Alvin goes out of control! Will Brittany find a way to restore the natural order of her very sisters or will she be forced to be second