Agnes and the other members of the Secret Knock Club decide to form a rock band and perform at a concert to raise funds to rent a dunk tank for the spring fair.
When the members of The Secret Knock Club learn that the spring fair will be without a dunk tank, they decide to raise money to rent a tank. Agnes, as usual, comes up with a Big Idea—a rock band concert. She’ll be the vocalist, the other club members will provide the music. But can Agnes sing? Do the others know how to play instruments? And what if Principle Not-Such-a-Joy’s dog “has an accident” in the tank as he did the year before?