When Sloe was tiny, her Papa disappeared and she and her mama went to live in a prison camp in the snowy north, in a time and place when there are no more wild animals. Mama's crime: teaching science, and her dedication to the hope that the lost animal species can be reborn. To Sloe, Mama's secret work is magic, as enchanting as Mama's tales of a bright city across the ice where they will be free.

Years later, Sloe is sent to a prison school, and Mama disappears. At 13, Sloe escapes, pursued by a mysterious man. With only hope to keep her going, Sloe sets out on a solitary 1000-mile journey. But she is not truly alone for Mama left Sloe a gift: the seeds of five missing species and the knowledge to bring them to life.