When Meg and her mother leave the big city for a charming cottage in a sleepy village, Meg knows that she will have the whole summer to adjust to a quieter way of life. Then she starts hearing the voice of a child calling out to her for help. The cries, she learns, come from an obsidian mirror embedded in the forehead of a toy horse and belong to the ghost of a young boy who has been trapped all alone for centuries. The boy, Jankin, desperately needs help to break free and only Meg can find his prison.

An ability is awakening in Meg, one that means she can open dimensional doorways through our world and worlds unknown. And somewhere, in among the labyrinth of mystical corridors that she must learn to navigate, is the cell that holds Jankin captive. Soon, though, Meg begins to ask herself