Matthew Heineman directs this documentary about the Mexican Drug War. Across both sides of the US-Mexico border, the feature follows two groups of vigilantes caught up in Mexico's war on drugs and the country's corrupt government. In Michoacán, Mexico, Dr. José Mireles, known as El Doctor, runs the paramilitary Autodefensas group that seeks to end the operations of the area's drug cartels, particularly the Knights Templar Cartel. Across the border, military veteran Tim 'Nailer' Foley heads the Arizona Border Recon as they try to prevent Mexico's drug wars from spilling into the US by guarding Arizona's Altar Valley, a 45-mile-long desert corridor referred to as Cocaine Alley.