After thirteen books, Abby is finally graduating from fifth grade. There's a lot to do before the big event, including finding the perfect graduation outfit. Once the ceremony is over, Abby plans to spend a quiet summer preparing for sixth grade. Then Abby's mother college friend, Laurie, and her young daughter, Wynter, arrive for an extended stay. Laurie--a musician--is trying to get her career back on track. She expects Abby to care for Wynter while she's out. Before long, Abby gets fed up. Abby's mom confronts Laurie, and Abby is able to reclaim her pre-middle school summer.