Phone service was down—a fuse had blown in the cell tower during a recent storm—and even though my arrival had been cleared with the government of Cherán in advance, the armed guard manning the highway checkpoint, decked out in full fatigues, the wrong shade to pass for Mexican military, refused to wave me through. My guide, Uli Escamilla, assured him that we had an appointment, and that we could prove it if only we could call or text our envoy. The officer gripped his rifle with both hands and peered into the windows of our rental car. We tried…