Camber the Heretic

"Deryni" (humans with enhanced psychic powers) and normal humans coexist in a feudal society reminiscent of medieval Europe complete with Catholic Church, until the death of the king provides enemies of the Deryni an opportunity to establish a new regime dedicated to their elimination, opposed by highly placed Deryni bishop Camber, having assumed a false identity since his purported death, and his family and friends.