The subject of this work is anomalies—those things that are between one state and another, neither dead nor alive, neither animal nor human. In this instance, they are the "spooks" (espantos) that inhabit the Maya area: the charcoal-cruncher, a disembodied head that goes off into the night to eat charcoal; the characotels, men who have turned into animals in order to steal chickens; and others. The victims chosen by spooks are likewise between two states: they are caught while asleep or drunk; or they may be humans who ignore social conventions and behave in "un-human" manner.

The Black-man of Zinacantan focuses on a small, super-sexed demon who possesses a six-foot-long, death-dealing penis and a penchant for mischief-making. This demon is known in Highland Chiapas as h'ik'al, the Black-man. Although h'ik'al's prototype may have been the bat deity, an ancient Maya god of sacrifice, the demon has been adapted to contemporary life. Sarah Blaffer analyzes the position of anomalies in societies and shows h'ik'al as a norm-offending, yet norm-reinforcing, specter, who by his character and actions demonstrates the proper sex roles for Zinacantec men and women.

The data for the study was recorded in Zinacantan, a Tzotzil-speaking Maya community, and in other Maya towns in southern Mexico and Guatemala; the study includes an analysis of tales recorded and translated by Robert M. Laughlin. The drawings that decorate the text were adapted by Virginia Savage and Joseph Barbieri. Besides being a comprehensive treatment of Maya demonology, the book demonstrates the newer approaches in comparative mythology of Claude Lévi-Strauss and others.