In the third installment of the Frank and the Puppy series, Frank and Sunny face their greatest challenge yet: an excitable little girl with no concept of boundaries. When Frank and Sunny's humans bring home their niece (or "nibling" as they call her) for a visit, it is a far cry from what they expected! Nelly has strong ideas about how to play and what constitutes fun including a nauseating basket ride around the house and a mandatory play wedding -- with costumes! -- between Frank and Captain Keith, the parrot. How will the friends survive the terror of a little girl?