With this complicated fantasy about family politics, bestseller Weeks (The Way of Shadows) moves into familiar territory. An unloved, orphaned boy is the offspring of someone important; twins assume each other's identities; an aged ruler clings to power. Weeks manages to ring new tunes on these old bells, letting a deep background slowly reveal its secrets and presenting his characters in a realistically flawed and human way. Gavin Guile is facing his final five years as leader of a magical college whose members turn colors of light into various materials. Seeking to rectify the lingering wrongs from the war against his twin, Dazen, he is instead forced to acknowledge a bastard son, face down a corrupt governor, and stop a challenge to the state religion. Frequent perspective shifts keep the reader guessing as to who is heretic and who is hero. Author tour. (Sept.)