At the end of State Road 170 lies Artemis, population 2500. The townspeople had sought out this remote corner of western Texas in hopes of living lives of solitude and independence. None of them realized that their small town would become a hot spot for Mexican drugrunners, whose turf battles have turned both sides of the Rio Grande into a war zone. Still, many of the locals would rather take the law into their own hands than get help from police chief Josie Gray, even when they're up against a cartel's private army.

After arresting one of the cartel's hitmen and killing another, Josie...