After watching the contestants on The Batter-Up Bake-Off Show whip up sweet treats, Anna, Isabel, Sadie, and Banana are ready to put their culinary chops to the test. The plan? To make the best-ever cookie recipe for the town library's bake sale!

There's only one problem: Isabel and Sadie have started hanging out with a girl named Monica, and suddenly she's all they can talk about. Anna's sure she, Sadie, and Isabel are complete as a trio, and winning the bake sale will prove it. But when Monica shows up with Sadie and Isabel for their big baking day things quickly turn from sweet to sour.

Can Anna win back the attention of her two besties, or will she learn that friendship--like cookies--is best when shared?