House of War — Judith Tarr

It is the dawn of the thirteenth century, and Richard the Lionheart has grown in strength and wisdom since he was crowned King of Jerusulem -- and dispatched the scheming sorcerer Sinan, who once endangered his very soul. But now the Old Man of the Mountain has returned...

Sioned, illegitimate half sister to the king and newly wed to an infidel sultan, has defeated Sinan before. Heir to both the faery Sight of ancient Wales and the demonic powers of the Devil's brood of Anjou, Sioned battled the sorcerer with the help of an army of the jinn. But this time Sinan is striking at the heart of his enemies by attacking their most beloved. And Richard will be forced to call upon a magic he is only just beginning to understand....