Plot
A suicide bombing by ISIS in a Kansas City grocery store kills 15 people. In response, the U.S. government orders CIA officer Matt Graver to apply extreme measures to combat Mexican drug cartels who are suspected of having smuggled the terrorists across the Mexico–United States border. Graver and the Department of Defense decide the best option is to instigate a war between the major cartels, and Graver recruits operative Alejandro Gillick for the mission. Graver also meets with private military company boss Andy Wheeldon to procure mercenaries, helicopters, and encrypted communication equipment for the U.S. to maintain plausible deniability while combating the Mexican cartels.
Gillick assassinates a high-profile lawyer of the Matamoros cartel in Mexico City while Graver and his team kidnap Isabel Reyes, the daughter of Carlos Reyes (kingpin of the Sonoran cartel, rivals of the Matamoros), in a false flag operation.
Graver, Gillick, and their team take Isabel to a safe house in Texas and stage a DEA raid pretending to rescue her from the Matamoros cartel. They take her to an American military base while the team organizes her return to Mexico. They plan to leave her behind in a Mexican Federal Police depot located inside territory controlled by her father's rivals to escalate the inter-cartel conflict further. However, after they cross into Mexico, the corrupt police escort turns against them and attacks the American Humvees. In the firefight that ensues, Graver and his team kill 25 Mexican policemen to escape the ambush. The dead policemen become mainstream news.
Amidst the chaos, Isabel, who realizes that Graver's team may have been behind her abduction, tries to escape and runs away into the desert. Gillick goes after her alone while the rest of the team returns to the U.S. Meanwhile, the American government determines that at least two of the suicide bombers in Kansas City were domestic terrorists, not foreign nationals, and thus were not smuggled into the U.S. by the cartels. To quell tensions with Mexico, the United States Secretary of Defense orders the CIA to abandon the mission. Learning that Isabel witnessed the Americans shooting the Mexican police, the Secretary orders the team to erase all proof of American involvement by killing Isabel and Gillick. Graver, in turn, warns Gillick and orders him to kill Isabel, but Gillick refuses and turns rogue to keep her alive. Gillick and Isabel have found shelter at an isolated farm in the desert for the night. Gillick knows that if they stay in Mexico, Isabel will be killed. With few resources, they disguise themselves as illegal immigrants and pay human traffickers to help them re-enter the U.S. Graver and his team fly covertly into Mexico by helicopter, tracking a GPS device that Gillick has activated and embedded into Isabel's shoe.
At the point of departure for the border, Miguel, a young Mexican American who has been recruited as a coyote, recognizes Gillick from an encounter in a Texas parking lot two days earlier. He alerts his boss, who takes Gillick and Isabel hostage. As a gang initiation, Miguel is forced to shoot a hooded Gillick in the head, leaving him for dead. Upset, Miguel abandons the gang and walks off by himself. Graver, having witnessed the apparent killing of Gillick via satellite imaging, tracks down and eliminates the Mexican gang. They find Isabel, and defying his orders, Graver decides to bring her to the U.S. and place her in witness protection. Meanwhile, Gillick regains consciousness, having been shot through the cheek. A gang search party chases him, but he kills its members by throwing a grenade into the pursuing car.
One year later, a now heavily gang-tattooed Miguel is in the Texas mall where he first saw Gillick. He enters the office of his gang contact, but instead finds Gillick waiting for him. Gillick says to a dumbfounded and intimidated Miguel: "So you want to be a sicario? Let's talk about your future."