'No rules this time,' federal agent Matt Graver (Josh Brolin) tells his operative Alejandro (Benicio Del Toro) with discernible relish, as he brings him back into the fold. The kind of film that sums up its approach in several such statements, the follow-up to the masterful, triple Oscar-nominated Sicario trades the original's suffocating suspense for a more mechanical brutality but still delivers a certain amount of satisfaction. Taylor Sheridan returns as scribe, while Stefano Sollima (who demonstrated his chops for layered crime thrillers with 2015's Suburra) takes over from Denis Villeneuve as director.

Mexico's cartels remain firmly in the movie's sights, with this sequel shifting the focus from the drug trade to human trafficking. When Isis suicide bombers hit a supermarket in Kansas City it appears they may have slipped into the country via the Mexican border. Reclassifying the cartels' operations as terrorist activity, the American authorities give themselves licence to come down on them, hard.

Ever-shady CIA man Graver is brought in by the US Secretary of Defense (Matthew Modine) and his deputy (Catherine Keener) and plots to disrupt the cartels' activities by recklessly setting them against each other. Meanwhile, we follow young Mexican-American Miguel (Elijah Rodriguez) as he is inducted into the business of people smuggling.

With the US-Mexico border a topical and incendiary issue, the film would seem to arrive at an opportune time. However, such is its weary worldview that it neglects to humanise the plight of those crossing, instead emphasising the callous disregard with which they are treated, particularly when Miguel is told to think of them like sheep.

Seen through the eyes of Emily Blunt's honourable FBI agent, the first film carried her sense of horror, outrage and fear at both the violence of the cartels and her own country's underhand tactics. Through Miguel and the daughter of a cartel kingpin who becomes a pawn for Graver's team (Isabela Moner), the sequel shows how young lives are ruined by association or involvement with criminals, yet the pair's character development is pretty cursory.

If both Sicario and Hell or High Water (for which the Sheridan was Oscar-nominated) had a certain hardboiled swagger, Sheridan's dialogue here feels more on the nose. Nonetheless, Del Toro and Brolin bring the full weight of their charisma to bear on this lesser beast. The way their characters function with grizzled unflappability has a ring of authenticity – Graver literally shrugs away the carnage and, after their convoy is attacked on a dirt road in a high-stakes sequence, him and his team simply dust themselves off with little more than irritation.

There's edge-of-the-seat action and Sicario 2 is shot with some style by Dariusz Wolski, while Hildur Guðnadóttir's score kicks out that familiar thunderous dread as she emulates the late Jóhann Jóhannsson's commanding work on the original. But, with the cynicism of its protagonists seeping into every pore, the film can feel emotionally one-note, and the narrative pivots with a somewhat deadened predictability. 'Fuck it all,' Graver says at one point. Although there are concessions to compassion, it never really convinces itself, or us, to care.

General release from Fri 29 Jun.