Los Angeles County sheriff ’s deputy Charlie Hood is attached to the ATF, working undercover on the iron river that flows across the U.S.-Mexican border. The diamond fillings he wears in his left canine glimmer, distracting the men who sell the illegal firearms that enable the unspeakable violence on both sides of the map. Spotting the sparkle when “Charlie Diamonds” opens his mouth is often their first step toward life behind bars.
 

Erin McKenna, a beautiful songwriter married to a crooked Los Angeles County sheriff’s deputy, is kidnapped by Benjamin Armenta, the ruthless leader of the powerful Gulf Cartel. But his demands turn out to be as unusual as the crumbling castle in which Erin is kept. She is ordered to compose a unique narcocorrido, a folk ballad that records the exploits of the drug dealers, gunrunners, and outlaws who have populated Mexican history for generations. Under threat of death, Armenta orders Erin to tell his life story—in music—and write “the greatest narcocorrido of all time.”

ATF agent Sean Ozburn is deep undercover supporting the sicarios of the Baja Cartel when he suddenly goes completely dark, his only communications being the haunting digital videos he sends to his desperately worried wife, Seliah. Charlie Hood must determine if Oz is simply chasing demons deeper undercover than anyone has ever gone, or whether his friend has suffered a permanent break with his mission and his moral compass.

This time around, Hood is running the California-Mexico border with the ATF, searching for the iron river – the massive and illegal flow of handguns and automatic weapons that fuels the bloody cartel wars south of the border. Gunrunners by nature aren’t exactly ethical, but the lengths they’ll go to, and the innocent lives they’ll risk, are shocking even to Hood.