Having literally gone from rags to riches, Alvin, Simon and Theodore didn't think their lives could get any better - and they certainly didn't think it could all go downhill. Their best friend and father figure Dave has met a woman, and while the chipmunks are happy to have a new face in their lives, they're super worried it could mean the end for them. Dave is going to Miami to propose and is planning on leaving his furry friends at home in Los Angeles. But after a serious misunderstanding, the guys believe that they are going to be abandoned forever. And so, they set out follow Dave to the sunny city to stop the proposal and save their friendship with Dave - while gaining yet more fans with their spontaneous musical exhibitions along the way.