A middle grade fantasy novel in which an orphan is pulled into a magical adventure. A green apple tree grows in the heart of Thirsby Square. Its leaves are a sad emerald and its apples a cheery peridot, and at its roots starts the story of Lottie Fiske. For as long as Lottie can remember, the only people who seem to care about her have been her best friend, Eliot, and the mysterious letter-writer who sends her birthday gifts. But now strange things and people are arriving on the island Lottie calls home, and Eliot's getting sicker, with a disease the doctors have given up trying to cure. Lottie is helpless, useless, powerless. Until a door opens in the apple tree. Follow Lottie down through the apple roots to another world - a world of magic both treacherous and beautiful - in pursuit of the impossible: a cure for the incurable, a use for the useless, and protection against the pain of loss.