Set in the Appalachian Mountains, The Secret of the Heart-Shaped Shell is the story of Lissa and Rylee. While the cousins have the relatable struggles of becoming teenagers, they also have a family mystery to solve. From one summer to the next, Lissa learns to overcome her insecurity and succeed in her passion of ballet. Rylee learns patience as she becomes a valuable volleyball player. Both girls learn to trust themselves, to realize their inner courage, and to take risks as they follow their dreams.