The Last Enchantment - Mary Stewart

Crowned and recognized as High King, Arthur melds the country together in a time of promise, as Merlin works in the shadows. But while unchallenged on the battlefield, sinister powers plan to destroy him in his own Camelot. n nArthur Pendragon is King Unchallenged on the battlefield, he melds the country together in a time of promise. But sinister powers plot to destroy Camelot, and when the witch-queen Morgause -- Arthur's own half sister -- ensnares him in an incestuous liaison, a fatal web of love, betrayal, and bloody vengeance is woven.n