The Chipmunks are arguing about their birthday so they ask Dave and he tells them that he doesn't know exactly. Later that night, Alvin points out that their mother would know their birthday so they decide to set off to look for her. The next morning, Dave finds The Chipettes preparing his breakfast and newspaper in the kitchen. The girls tell him what The Chipmunks set out to do causing Dave to go in pursuit.
The boys journey to Eagle's Peak based off advice given by a Ranger, asking animals along the way. About to give up, the boys are chased by a boar until they collapse in front of a hollowed-out tree. After being found by Ally, the house-sitter for Vinny, the brothers are immediately recognized as Vinny's boys once she returns. Meanwhile, as Dave and the girls look for the missing boys, Brittany falls off a cliff and Dave rescues her. Back in Vinny's house, Vinny reminisces of the days they were babies before going to bed.
The next morning, she had prepared them a breakfast of maple leaves, berries, and nuts, which the boys were not used to. Alvin knocks the bowl of berries, clearly upset at Vinny for leaving them. Vinny explains to Alvin that the winter was very severe and the only way for them to survive was to live with the nice man in the house nearby. After explaining, Simon and Theodore convince Alvin that he can't expect her to leave the forest. The boys are again chased by the boar, but Vinny puts herself in its way saving them. The next morning, Vinny surprises her boys with a birthday party. The girls and Dave finally find the boys and are invited to join the party.
- This special was the first appearance of The Chipmunks' mother Vinny.
- This was the other special based on the Ruby-Spears cartoon series, also appearing in syndication as a regular episode.