Well financed and well armed, the drug cartel gang known as Los Zetas operates with seeming impunity in Mexico. After deadly bombings on both sides of the Rio Grande River, a majority of American lawmen tend to blame the Zetas for the carnage. ATF explosives expert Pam Robinson disagrees. She suspects an Islamic terrorist connection, which puts her at odds with her own boss, most of official Washington, and Texas Rangers Captain Steve Oliveras. When she and Oliveras are assigned to the same multi-agency, cross-border taskforce, they clash on both professional and personal levels. They must come to terms with one another just to survive in the ensuing lethal crossfire.