The Cupcake Club comes to Katie’s defense when a surprise at school leads to unfair gossip. When Katie’s mom says it’s time for Katie to meet her new boyfriend, Katie is excited and nervous. She thinks she’s prepared, but she’s shocked instead. Her mom’s boyfriend is Jeff Green—as in Mr. Green, a math teacher in her grade! Katie tries to act as normal as possible, but when mean girl Olivia finds out, she tells everyone that Katie is getting special treatment because her mom is dating a teacher. How can Katie stop Olivia and deal with all the new events in her life? It’s the Cupcake Club to the rescue, as Katie’s friends come to her defense, including an unexpected ally.

Can the new Fashion Club be the icing on the cupcake for Mia, or is she in over her headshot? When fashionista Mia hears someone is starting a Fashion Club at school, how can she resist? But can she manage to take part in two clubs at the same time? And what will her Cupcake Club friends think about this? Worst of all, Mia’s frenemy Olivia Allen wants to be in charge of the Fashion Club. Can Mia and Olivia make peace long enough to survive a fashion show?

The girls realize that it is great to have friends and they are a lot like cupcakes you can't have enough and they are good in all combinations.

When Katie brings her maybe-someday stepsister to Cupcake Club, she gets her first taste of sibling rivalry—and it’s not very sweet! Katie’s mom asks Katie for a huge favor: will she spend some time with Emily, her boyfriend’s daughter? Katie agrees and brings Emily to a Cupcake Club meeting. Things go well—almost too well. Everyone likes Emily so much, Katie wonders if her friends like Emily more than they like her! And if her mom marries Emily’s dad, will Emily become her favorite daughter? Katie is an only child, so all this sibling stuff is new to her. She’s starting from scratch!

Emma's younger brother Jake has tonsillitis and makes life difficult for Emma, while the Cupcake Club girls are spoiling him with cupcakes and little gifts.

Mia learns to balance style and substance when she has to get glasses AND braces. Fashionista Mia gets some unflattering news from Katie’s mom, Dr. Brown: She needs braces. And just when Mia thinks things can’t get any worse...they do. Her teacher is concerned that Mia is squinting in class. A trip to the opthamologist confirms it: Mia needs glasses, too! Mia is miserable until her stylish mom comes to the rescue with a plan and a very chic middle school look. And her wonderful Cupcake Club friends reassure her that glasses and braces don’t get in the way of all they really see: the same old Mia.