Winicker Wallace is delighted to learn that Mademoiselle Bennett's nephew will be joining her class. His name is Roger and just like Winicker, he's American. Winicker volunteers to show Roger all of the things she's learned to love about Paris, but Roger isn't interested. He would rather disrupt Mademoiselle's class, play mean tricks on Mirabel Plouffe, and get Winicker and Mirabel into more trouble than they've ever imagined. When it appears Roger has gone too far, Winicker learns the importance of standing up for herself and her friends, and that telling an adult is not the same as tattling.