Saint Camber: Vol.2, in the Legends of Camber of Culdi
When Camber of Buidi, master of arcane Deryni powers, led a successful revolution against Imre, his sister Ariella, plotted war against Cinhill, her brother's successor. But Cinhill didn't want a fight, he didn't want power, and it was up to Camber to save crown and country....