Fifth-grader Sadie and her friends in the cupcake club face their toughest challenge yet when they compete in the televised Battle of the Bakers.

In the midst of the excitement of Jenna's mom's wedding in Las Vegas, for which the girls of Peace, Love, and Cupcakes are making a giant wedding cupcake tower, Jenna begins to worry about changes the marriage may bring.

Juliette invites the cupcake club girls to London to cater her boyfriend's West End acting debut, and while there Lady and Lord Wakefield ask them to build a cupcake London Bridge for their daughter's birthday.

Worried about meeting her biological father, Katie is blindsided by the news that her mother's boyfriend intends to propose to her mom.

Aspiring to win the science fair with a project that proves that cupcakes are good for you, Alexis finds her ambitions challenged by her crush's association with another girl and a cupcake order for a mean girl's sweet sixteen.

When Alexis decides she wants to be more like her popular older sister, Dylan, she tries out for cheerleading, without really thinking about what that entails, including that her sister was a star on her cheerleading squad.

When Emma's little brother Jake looks after the neighbor's dog in preparation for getting his own puppy, the pet goes missing and Emma and the rest of the girls have to find it before the owner comes home.

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.

"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...