Teddy and his family are excited to welcome baby sister Ashley. However, as time goes by, Teddy becomes unhappy and is lead to believe that no cares about him any more, and having a sister won't be fun. He decides to hide out in the tree house to see if anyone will look for him.

Teddy learns that having a new family member doesn't mean that his family loves him less. He also learns that being a big brother is rewarding, but comes with responsibilities.