In the fourth volume of The Book of the New Sun, Severian completes the tale of how he rose from an apprentice torturer to Autarch, ruler of the Commonwealth. After fighting in the war against the Ascians, he encounters the dying Autarch, who urges Severian to eat his brains and thereby gain his memories. Severian then returns to the Citadel and ascends to the throne, discovering the secret that may save Urth from destruction.