Siberia

When Rosita was tiny, her papa disappeared. She and her mama had to go and live in an ugly place, outside the warm city in the frozen wilderness. Rosita didn't know the ugly place was a prison camp, and she didn't understand her mama's magic. She only knew she had to keep the secret until Mama said it was time to start on the great journey, through the forest and across the sea of ice, to safety. But once Rosita grew up to be a tough, cynical girl called Sloe, hardened by grim years in the prison school, Mama was gone. Sloe had to make the journey alone, pursued by a mysterious and all-powerful enemy, and carrying the living treasure that she knew was the hope of the world. Sloe becomes a heroine, equal to anything, in this dazzling blend of science, adventure and fairy tale.