Book 4 of The Hounds of Annwn.
George Talbot Traherne, the human huntsman for the Wild Hunt, is preparing for the birth of his child by exploring the family papers about his parents and their deaths. When his improved relationship with his patron, the antlered god Cernunnos, is jeopardized by an unexpected opposition, he finds he must choose between loyalty to family and loyalty to a god.
He discovers he doesn't know either of them as well as he thought he did. His search for answers takes him to the human world with unsuitable companions.
How will he keep a rock-wight safe from detection, or even teach her the rules of the road? And what will he awaken in the process, bringing disaster back to his family on his own doorstep? What if his loyalty is misplaced? What will be the price of his mistakes?