Emily Blunt, left, Josh Brolin, standing at center, and Benicio del Toro, right, play members of a mysterious task force that barrels through the streets of Juarez, Mexico, in black SUVs. (Richard Foreman Jr SMPSP/Lionsgate)

‘Sicario” certainly knows how to make an entrance.

The movie opens with a SWAT truck crashing through the front wall of a drug lord’s house, prompting a chaotic gunfight. Before the audience has even gotten its heart rate under control, a sickening discovery is made: Forty-two bodies have been hidden behind the drywall, each one with a plastic bag covering its decomposing head.

And that’s before a bomb, rigged as a booby trap, rips off a man’s arm.

Is this a horror movie or an art-house morality tale? The reputation of director Denis Villeneuve — the man behind “Incendies,” “Prisoners” and “Enemy” — suggests that it’s the latter. But the distinction won’t make your nightmares any less hideous.

The leader of that unfortunate FBI tactical team is Kate Macer (Emily Blunt). A by-the-book agent based in Arizona, she’s frustrated with losing the war on drugs, which inspires her to volunteer for a mysterious interagency task force. The head of that team, Matt (Josh Brolin), dresses like a surfer and refuses to share many details of their mission with Kate, other than the fact that they’re heading to El Paso.

They’re not. With little explanation, they drive across the Mexican border to Juarez, where bodies are shown hanging from bridges and where they don’t technically have jurisdiction. So much for following rules.

For the viewer, Kate is a proxy, struggling to figure out why she was recruited for this vague, possibly illegal assignment and what, exactly, Matt’s job is. Does he work for the CIA or Defense? And who is his mysterious right-hand man, the aloof, lupine Alejandro (Benicio Del Toro)? When Kate asks the Mexico native whom he works for, he tells her, “I go where I’m sent.” And that’s one of their more substantive conversations.

In “Sicario,” which translates as “assassin,” the suspense is relentless, propelled by a driving score by Academy Award nominee Jóhann Jóhannsson. As Kate, Alejandro, Matt and a team of military operatives recently returned from Afghanistan barrel through the streets of Juarez in black SUVs, the pounding beat recalls a war drum. The sound alone is enough to induce sweaty palms.

Villeneuve keeps the audience on edge by alternating quiet moments with sudden bursts of action. Just before that truck tears through the house at the beginning of the movie, for example, the camera settles on a solitary man watching television in his living room. Every scene of calm, potentially, is trip-wired for an explosion.

But for all its chilling tension and horrific imagery, “Sicario” is also a beautiful movie. Maybe cinematographer Roger Deakins will finally win the Oscar he deserves. (The 13th time’s the charm?) His work here is stunning, whether the camera is capturing dust floating around a sunny room or framing the silhouettes of agents disappearing into the horizon at dusk, as if they’re being swallowed whole by the land.

If “Sicario” falters, it’s only in its attempt to be more than a thriller. Villeneuve’s movies occupy a spectrum between thought-provoking and mind-bending, and it’s clear that he wants to guide Taylor Sheridan’s script into similar territory. The movie makes occasional detours away from Kate to show the everyday life of a Mexican police officer (Maximiliano Hernández) at home with his wife and young son in Sonora. Inevitably, that man’s story and the main narrative will intersect. But the collision course isn’t provocative enough to justify the diversion.

The movie works best when it sticks with Kate, whose fear is palpable and contagious. In the grim world of “Sicario,” the life-or-death situation that she finds herself in may not be the most geopolitically shocking, but it makes for electrifying drama. And sometimes that’s enough.

An earlier version of this story incorrectly stated the Texas city where Kate thinks she’s going. It’s El Paso, not San Antonio. This story has been updated.

R. At area theaters. Contains strong violence, grisly images and language. In English and some Spanish with subtitles. 121 minutes.