Presidio County, Texas, sits against the border in a remote region of the Chihuahuan desert along the Rio Grande. The river marks the legal boundary between Texas and Mexico, but in reality, la frontera's unique blend of culture and language does not respect fences. Texana Jones owns and operates a trading post in this desolate region. On El Dia de los Muertos, the Day of the Dead, she is delivering supplies to reclusive Rhea Fair, a curandera, or healing woman, and finds her dead. When the sheriff blames the death on the random violence of drug smugglers, Texana refuses to accept the explanation, particularly since the violent deaths of two close friends six months earlier were attributed to the same vague motivation. Taking a closer look at the curandera's last few days, Texana finds many unusual events, from the disappearance of Rhea's handyman, Trinidad, to the visit of a young woman driving a rental car. Texana follows a trail to the border cities of El Paso and Juarez and up to San Antonio, where an encounter with a stranger points her toward home. It is in the desert, where secrets are hidden so easily, that she uncovers a powerful motive for murder.

Martin, Allana