Following a mission at home that goes badly wrong in a creative but flawed way, an eager yet inexperienced FBI agent named "Kate" (Emily Blunt) is invited to join a group tasked with retribution. The team will be led by "Graver" (Josh Brolin), and includes the quiet, mysterious “Alejandro” (Benicio Del Toro). Kate isn’t impressed by Alejandro's demeanor, and feels uneasy about the whole undertaking, but they head to El Paso in an attempt to halt the war against drug cartels that are growing increasingly powerful and well-equipped. Their goal is not to interfere with how these operations function, but rather to pinpoint those at the top and eliminate them. Kate (and the audience) quickly discovers this mission operates far outside legal boundaries; numerous regulations are bent, disregarded, or outright shattered as the team must use their enemies' own methods if they hope to locate their main target, "Manuel Díaz" (Bernardo Saracino). She also realizes she’s not being fully informed, with information released in a way that often makes her want to quit. Despite this, she continues and as events unfold, we are shown a brutal, organized, and internal network easily capable of outmaneuvering its supposedly more knowledgeable and equipped pursuers. It's then that it becomes clear “Alejandro” has his own motivations, and anyone who stands in his way should be wary. Brolin’s role is fairly minimal, but Blunt gives a compelling performance as "Kate" confronts significant challenges to her ethics and beliefs. Del Toro doesn't have much dialogue, but he effectively portrays a menacing character whose allegiances remain uncertain for quite some time. The film begins with intensity and takes the time to develop believable characters, even if they aren’t particularly appealing, while presenting what may be as accurate a depiction of the battle for control of the billion-dollar narcotics trade as we're likely to see on screen.

Source on TMDB