Frank and Sunny’s humans are bringing home their nibling for a visit. But what exactly is a “nibling”? Frank says it’s a small bite of something, and Sunny thinks that sounds delicious.

But then there is a knock on their door, and this nibling 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?