The chipmunks are up to their usual shenanigans when they come to believe that Dave, who is visiting New York with his girlfriend, is going to propose. They fear they will lose Dave to his fiancee and her son - their potential awful new stepbrother - and decide to take action. With only three days to get to Dave and stop the proposal Alvin, Simon and Theodore decide to take a road trip to New York to save the day!
