Deerskin — Robin McKinley

As Princess Lissar reaches womanhood, it is clear to all the kingdom that in her breathtaking beauty she is the mirror image of her mother, the queen. But this seeming blessing forces her to flee for safety from her father's wrath. With her loyal dog Ash at her side, Lissar unlocks a door to a world of magic, where she finds the key to her survival--and an adventure beyond her wildest dreams...