A boy's family travels to the Allegheny Mountains in order for the entomologist father to find an undiscovered moth he remembers seeing there in his youth. Over the course of the summer, the boy's sister, who suffers from autism, finds she can speak the language of various insects and creatures of nature, allowing her to understand the world around her for the first time in her life. And as the boy himself comes of age, he discovers that he speaks a different sort of language as well. As each person journeys closer to their true nature, tension is eased within the sometimes strained relationships of this unique family.