New York Times bestselling fantasy author Tamora Pierce returns to the world of the Circle of Magic Quartet.

Evvy, a young stone mage in training, is accompanying her mentor, Rosethorn, and another dedicate from Winding Circle while they investigate mysterious happenings on the island of Starns. Her job is to listen and learn, but, being Evvy, she can't just keep quiet and do nothing. With the help of Luvo, the rock being she befriended at her home in Yanjing, Evvy discovers the source of the problem -- a long-dormant volcano. Now she and her friends must save the islanders from impending disaster -- if only Evvy can use her talents to avert the certain destruction that looms ahead.