Inhabiting the Sierra Madre Occidental of southwestern Chihuahua in Mexico, the Tarahumara (or Raramuri) are known in their language as the "foot runners" due to the way in which they must navigate their rugged terrain. This book offers an accessible ethnography of their history, customs, and current life, accompanied by photographs that offer striking images of these gentle people.

The subtitle of the book derives from the Tarahumara's belief that the soul works at night while the body sleeps and that during this "day of the moon" both the spirits of the dead and the souls of the living move about in their mysterious ways.