On a hot summer day in Los Angeles, thirteen-year-old Josephine "Joey" Rivera - a misfit in junior high school but a born musician - meets a disquieting young man named Indigo who plays ghostly, haunting music on a horn the hue of a conch shell. The sound of his music stays with her, distant and beguiling, until she follows it down an ordinary street and across an unseen border into a magical world called Shei'rah. There, satyrs, water nymphs, and six-inch-long dragons live side by side with phoenixes and two-headed serpents and the Eldest - the unicorns whose music is the soul of Shei'rah. There are dangers, too - from swarms of tiny, terrible flying creatures called perytons, and from a strange disease that is blinding the Eldest. To Joey, Shei'rah feels like home - but she already has a home across the Border, in our world. She has school and a family and a feisty, beloved grandmother, Abuelita, whom she visits every Sunday in a nursing home. There's also gruff old John Papas, whose dusty instrument-repair shop Joey cleans in exchange for music lessons, and who may know something about the Eldest himself. Within these two worlds whose borders merge mysteriously, Peter S. Beagle spins a tale of one girl who can make a difference. The Unicorn Sonata also tells us that our true home is often right around the corner, if we'd only open our eyes - and our ears - to find it.