Alvin plays a prank on Theodore to get him to eat a dog biscuit and puts shoe polish on Simon's telescope to give him a black eye. To get even, Theodore, with Simon's help, plays a trick on Alvin and makes him think that he is actually turning into a were-dog. Simon convinces Alvin to do all their chores in exchange for not telling Dave before he performs some research. According to one of Simon's books on were-dogs, the only way for Alvin to save Theodore from turning into a were-dog forever is for Alvin to perform a ritual under the full moon. After the ritual, Alvin's fooled into believing that Theodore has transformed completely and sets out to find him when he is caught by an animal control employee. When Alvin is accidentally locked in a cage at the pound, he calls Dave and finds out the truth about Theodore.
- Part of the Alvin and the Chipmunks: Hair Raising Chipmunk Tales VHS.
- Part of the Trick or Treason and Halloween Collection DVDs.