At the outset of Sicario, we learn that its title, Spanish for “hit man,” also refers to the Jewish zealots who used murder and other extremist measures to expel the Romans from first-century Judea. Both allusions apply to the shadowy U.S. government task force at the center of director Denis Villeneuve’s bleak appraisal of the modern border war on drugs.

In an extended cold open, FBI agent Kate Macer (Emily Blunt) and her SWAT team raid a booby-trapped house of horrors, owned by cartel bigwig Manuel Diaz (Bernardo Saracino), in Phoenix, Arizona. Soon, Kate’s minders and an enigmatic spook named Matt (Josh Brolin) recruit her to a black ops unit whose objective is “to dramatically overreact” to drug smuggling from Mexico. Kate becomes an interagency pawn for a paramilitary posse whose missionand the opposition to itforced it to chuck its moral compass long ago.

The hitman is Alejandro, a former South American prosecutor turned assassin, brilliantly played by Benicio Del Toro. Alejandro is Matt’s spear tip, a cold-blooded crusader with a hatred of Mexican drug lords and a mysterious backstory, all shrouded behind Del Toro’s world-weary eyes. Villeneuve embeds us in one bravura action set piece after another, including a white-knuckle extraction of Manuel’s brother from a prison in Juarez, a rotting hellscape where headless corpses sway from overpasses and tracers illuminate the night sky.

The cast is uniformly convincing, especially Del Toro, Brolin and Blunt. Kate actually proves to be a more vulnerable character than Blunt has played in recent action-movie roles. But the real star is the indomitable cinematography of Roger Deakins, the award-winning director of photography for Villeneuve’s similarly nihilistic sleeper hit, Prisoners. Deakins traverses the harsh Tex-Mex terrain from a variety of viewpoints: God’s eye, haloed horizon, even a night-vision incursion into a desert smuggling tunnel.

The film loses its bearings in the final act, when Alejandro goes full-on Anton Chigurh. Still, Villeneuve and Deakins’ taut tableau is as haunting as its subject matter, like the dark spawn of No Country for Old Men and Zero Dark Thirty. There’s little here that gets at the root causes of the drug war; we see only its cruel, corrosive effects. When Kate naively asks how cartels are organized, Alejandro sighs, “You’re asking me how a watch works. For now, just keep your eye on the time.”

This article appeared in print with the headline “Over the borderline”