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 are 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 the threat of death, Armenta orders Erin to tell his life story - in music - and write "the greatest narcocorrido of all time."

As the mesmerizing music and lyrics of Erin's song cascade from the jungle hideout, they serve as a siren song to the two men who love her: her outlaw husband, Bradley Jones, and the lawman, Charlie Hood - who together have the power to rescue her. Here, amid the ancient beauty of the Yucatecan lowlands, the long-simmering rivalry between these two men will be brought closer to its explosive finale.