Twelve houses, book 3: Dark moon defenderSharon Shinn2006

National bestselling and award-winning author Sharon Shinn continues her entrancing saga of the Twelve Houses with a story of hidden magics and forbidden love...
The King's Rider Justin has been dispatched to watch any suspicious activity at the convent that houses the fanatical Daughters of the Pale Mother. Worshippers of the moon goddess, they believe all magic-wielding mystics are evil. Yet, in their midst, a young novice named Ellynor possesses the gift of healing and the ability to move through the night unobserved. Assuming the guise of a stablehand, Justin befriends Ellynor --and love blossoms between them. And when he discovers her magical talents, Justin will risk everything--his own secret, the trust of his friends, even his very life--in order to save her...