Things are slow at the cupcake shop this summer, and so when Mia's dad invites her on a long weekend trip to meet some of his college friends, she jumps at the chance—especially when she hears they have daughters her age. It turns out the girls work in an ice cream shop. Not only does Mia end up making new friends—she comes back with a new invention for the Cupcake Girls: an ice-cream cone cupcake!