During a costume visit to the zoo, Alvin finds himself mistaken for a real Tasmanian devil. Soon, Alvin is stuck in the Tasmanian devil's cage and the real animal, goes home to the Sevilles'. The mix-up creates problems all around, especially when Simon reads that the Tasmanian devil is scheduled for surgery. Can Dave and the boys get to Alvin before the operation?!

While Dave is working on an important new song for the music festival, the Chipmunks are upstairs making a mess of their bedroom. Dave orders them to clean their room. But in the process, they accidentally ruin Dave's new song. Can they fix it in time for the big performance?