Sam's briefing to his junior agents had been fairly matter-of-fact: "To the west of us between Nogales and Yuma is some of the hottest and most inhospitable conditions for human survival imaginable. When the crossers came through there last summer we lost about forty, and that's just the bodies we found. There could have been hundreds, we don't know for sure. There's no water in that area. Our presence there is minimal since the environmental conditions offer sufficient 'enforcement' presence. We mainly try to intercept the crossers before their misguided trek becomes fatal. We figure our new program will persuade them to move east of Nogales, into the San Pedro area, where we'll be waiting."
The new program he mentioned entailed a mix of enforcement strategy, fear, and wonder. At the eastern end of this inhospitable region, west of Nogales, about a dozen deaths within the past several years had been labeled "suspicious." Bodies, or remnants, had been stashed in the brush or hidden in caves. Typical remains consisted of weathered and dismembered body parts, and frequently just scattered bones. Very few skulls had been recovered with the bodies, which seemed odd to Border Patrol forensic scientists. This fact also heightened the suspicion of the crossers and fueled a devil myth. Reports of human remains usually came to the Border Patrol from hunters. Mexican crossers seldom made official reports but no doubt encountered many more remains than did hunters. Discoveries by crossers eventually reached law enforcement through a variety of channels as each body was immortalized with exaggerated tales that collectively created an ominous death legend among crossers. That people had died was certain. What had killed them was unknown. Between the certainty and the unknown, the Mexican psyche created a supernatural agent of death, El Diablo de la Frontera, the Border Devil. In the minds of many who thought about crossing into the U.S., this demon lurked along the center of Arizona's border with Mexico, an area that became known to crossers as Satan's Crossing.
The search for El Diablo became the obsession of Agent Sam Logan, who partnered with a local rancher to eventually discover the killer. Along the way of Logan's investigation, his supervisor, Darrel Yost, thwarted Logan's actions. Yost was seeking the killer along a different trail, a self-serving one.
As the plot evolves, weaving through various killers at the border, the truth, then the whole truth...and eventually "nothing but the truth" emerges as the major cause of crosser deaths. The journey of Logan's dedicated enforcement effort reveals the moral decay that surrounds the seemingly simple act of a migrant heading north into the United States.
One way or another, based on desire or necessity, fueled with emotion or logic, each one of us starts out on a path and eventually crosses a line.