Master Engineer Kasha lives in hiding. As a Tanoa and a woman, she has no legal right to her title, and risks expulsion or even execution if the Guild discovers her identity. For over a year she has served as the City Engineer of the Andalano city of Wingmount, home to the Winged Riders and their pegasus mounts.
Now, though, her people need her. The last of their Earth Shamen is trapped in the mountains, holding back a volcanic eruption so that the rest of her people can escape. Saving her is a job for only the greatest of all engineers, and that happens to be Kasha.
But when her kinsman, Ahote, breaks the most sacred law of the Winged Riders, an alliance with him means certain death. Kasha must work alone to solve the most difficult engineering problem of all time before the summer months are done and winter comes to claim the life of the Shaman and the hope of her people.