Grover's Overtures is part of a series of books designed to introduce children to music concepts. Grover is thrilled because he has been assigned to play the cannon in the Monsterpolitan Opera performance of the 1812 Overture. However, Grover gets lost, pushes the cannon up stairs and down hallways, and stumbles upon the overture to Carmen (starring Placido Flamingo), a can-can, The Barber of Seville, and the William Tell Overture. Elmo the cymbal player, joins him halfway through. They finally arrive and give stirring performances, but an exhausted Grover decides next time, he'll just play a trumpet solo.