The ice is advancing, the Corridor narrowing, and the empire is under siege from the Scithrowl in the east and the Durns in the west. Everywhere, the emperor's armies are in retreat. Nona faces the final challenges that must be overcome if she is to become a full sister in the order of her choice. But it seems unlikely that she and her friends will have time to earn a nun's habit before war is on their doorstep... The searing conclusion of the thrilling epic fantasy trilogy.