On a summer night, Henry Day runs away from home and hides in a hollow tree. There he is taken by the changelings—an unaging tribe of wild children who live in darkness and in secret. They spirit him away, name him Aniday, and make him one of their own. Stuck forever as a child, Aniday grows in spirit, struggling to remember the life and family he left behind. He also seeks to understand and fit in this shadow land, as modern life encroaches upon both myth and nature.