For Mildred Hoppelt her third year at the Graustein Academy begins. And in just a moment, Mildred and her friends get themselves into a difficult situation. So Mrs. Graustein suggests that the girls join the Boiler Club. This Boiler Club is a circle for promising young witches. But Esther Edel of all people, the archenemy of the friends, is the leader of this club for young witches. And Esther insists that the candidates must first pass an entrance exam.