The Cupcake Club questions its loyalties when Mia makes friends with a mean girl in disguise. There's a new girl in town, and Mia tries to take her under her wing. But Olivia Allen is not so nice; as a matter of fact, she might be even meaner than Sydney Whitman! Mia's been saving for weeks to buy a new pair of shoes, but when Olivia asks to borrow money, Mia gives it to her—only to find out Olivia spends the cash on the exact same shoes Mia has been saving up for! Plus she makes fun of the other Cupcake girls and tells Mia she shouldn't be friends with them. Will Mia see Olivia's true colors before she wreaks havoc on the Cupcake Club?