American action movies about the drug cartels (David Ayer’s Sabotage, Oliver Stone’s Savages) have a high bar to clear: unless they bring some greater understanding of the crisis, their portrayal of the cartels’ barbarism seems like crass exploitation. This contribution to the subgenre is plenty violent, but it delivers light as well as heat; longtime actor Taylor Sheridan, making his debut as screenwriter, diligently explores the murky waters where law enforcement merges with national security. Emily Blunt, tough as nails, plays an Arizona FBI agent who’s recruited for an elite anticartel task force and soon realizes it’s a shadowy CIA operation; Josh Brolin is the smooth cowboy running the show, who will stop at nothing to smash the criminal organization that hangs mutilated bodies from the bridges of Juárez. This is suspenseful stuff, but hanging over the action is the pungent smell of social failure, as the drug war turns both sides into monsters. With Benicio Del Toro.