The novel centers on a young boy named Beto, who has been left by his mother to be raised by his Spanish grandmother Josephina and Yaqui grandfather Manuel, both of whom carry on the spiritual traditions of their cultural heritages, Manuel as a shaman and Josephina as a curandera.
As with other methods of modern curanderismo, this form of prayer healing is heavily influenced by Roman Catholicism as well as the indigenous traditions of a given region.
Tradition says, in all different variants, that the Caballucos del Diablu (Damselflies, literally "Devil's little horses") and the witches lose their powers after dusk and the curanderos gain control over them; plants as the four-leaf clover, the fruit of the elder berry, the leaves of the willow, the common juniper or the tree heath among others cure and bring happiness if they are collected at dawn.