Fifty-seven years later, the enigmatic architects disappeared, leaving behind for the people of New York the Old York Cipher—a puzzle laid into the shining city they constructed, at the end of which was promised a treasure beyond all imagining. By the present day, however, the puzzle has never been solved, and the greatest mystery of the modern world is little more than a tourist attraction.Tess and Theo Biedermann and their friend Jaime Cruz live in a Morningstarr apartment house—until a real estate developer announces that the city has agreed to sell him the five remaining Morningstarr buildings. Their likely destruction means the end of a dream long-held by the people of New York. And if Tess, Theo and Jaime want to save their home, they have to prove that the Old York Cipher is real. Which means they have to solve it.

    They hope this sacrifice will keep her from terrorizing their town. But the witch in the forest, Xan, is kind and gentle. She shares her home with a wise Swamp Monster named Glerk and a Perfectly Tiny Dragon, Fyrian. Xan rescues the abandoned children and deliver them to welcoming families on the other side of the forest, nourishing the babies with starlight on the journey.  One year, Xan accidentally feeds a baby moonlight instead of starlight, filling the ordinary child with extraordinary magic. Xan decides she must raise this enmagicked girl, whom she calls Luna, as her own. To keep young Luna safe from her own unwieldy power, Xan locks her magic deep inside her. When Luna approaches her thirteenth birthday, her magic begins to emerge on schedule--but Xan is far away. Meanwhile, a young man from the Protectorate is determined to free his people by killing the witch. Soon, it is up to Luna to protect those who have protected her--even if it means the end of the loving, safe world she’s always known.