In this mysterious tale set in ancient Mexico, something unearthly happens when a boy enters a forbidden cave. No curandero can change him back. Only the nahual, a shape-changing magic worker, can see beyond the horizon: "You are destined," he tells the boy, "to show the world something new." Twenty years later, the boy is a young man, known to village children as "Uncle Snake." Finally, it's time to discover the glorious change that awaits him. On this third collaboration, Matthew Gollub and Leovigildo Martínez have woven a captivating story, again set amid the rich folk culture of Mr. Martínez's native Oaxaca.