In times of pulverising change and social turbulence, when traditional political categories seem wanting and standard institutional processes falter, reality often manifests itself most vividly in culture and artistic expression.

So it is with Sicario 2: Soldado, which opens on Friday: a pulsing, nerve-shredding thriller set on and around the Mexico-United States border and its infernal plains of suffering, desperation and conflict.

Joining the very short list of films that are the equal of, or superior to, their predecessors – The Godfather Part II, French Connection II, Aliens – the movie continues the story of CIA agent Matt Graver (Josh Brolin) and Alejandro Gillick (Benicio del Toro), a former prosecutor turned assassin from the border city of Juárez who seeks revenge on the drug lords who killed his family.

Like the original, Sicario 2 pitilessly exposes the follies of the war on drugs and the stop-go strategies adopted by the politicians to whom the pair ultimately answer. There is a fresh twist, in Washington’s fear that the porous southern border has become an entry point for Islamist terrorists. So, once again, the duo is set loose to wreak havoc, pit the cartels against one another and thus – in theory – enable their political masters to restore a measure of order thereafter. Needless to say, order is not what this reckless plan delivers, and a kidnap plot intended to flush out one of the drug barons goes seriously wrong.

The narcotics trade and fundamentalist terrorism are staples of the modern thriller. But the true psychological backdrop of Sicario 2 is the phalanx of migrants who trudge through its demented battlefield of sand dunes, rusty houses and flying shrapnel, determined to seek a better life, exploited horribly by human traffickers and treated as subhuman interlopers by a nation that used to welcome “huddled masses yearning to breathe free” – as is made clear on the Statue of Liberty.

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Director Stefano Sollima and writer Taylor Sheridan can scarcely have known that their film’s release would coincide with the Trump administration’s deplorable separation of immigrant families at the border and the global outcry that has followed. But it is impossible to watch Sicario 2 and be unaffected by the deeply uncomfortable resonances.

I was lucky enough to host a preview of the movie at the weekend on behalf of Drugstore Culture – a forthcoming culture and politics magazine of which I am editor – followed by a question and answer session with del Toro. He suggested the film fits a well-established genre of border movies: one thinks of Alejandro Galindo’s Espaldas Mojadas, Orson Welles’s Touch of Evil and, of course, Steven Soderbergh’s Traffic (for which del Toro won an Oscar). And that is true.

But a genre movie can capture a moment, or cut through political babble to communicate the nuanced interaction between policy and people’s experience. The heart-stopping scenes in which del Toro’s character is seeking to cross into the US, posing as the father of a fugitive teenage girl, are a stunning reproach to Trump’s vile description of unauthorised migrants as “animals”.

The president may have had to retreat on the specific question of child separation – hastily signing an executive order – but terrible damage has already been done, the bureaucracy involved is shambolic, and perhaps 2,000 small children are still languishing in the disgustingly named “tender age” migrant shelters.

Who would have thought that the United States in 2018 would be afflicted by such dystopian euphemisms? Why is the bigoted buffoon behind this outrage still being welcomed by Her Majesty’s government on 13 July and rewarded with an audience with the Queen? And before you reel off all the dictators and despots that have been granted comparable treatment, stop and remember that the US is supposed to be our closest ally, our partner in the preservation of liberal democracy and a hyperpower held to a higher standard. If ever there was a moment for Theresa May to show that she stands for more than just carrying on, this is it.

Facebook Twitter Pinterest Shoes and toys left at the border in Tornillo, Texas, where children have been housed after being separated from adults. Photograph: Brendan Smialowski/AFP/Getty Images

So much is at stake. It is one of the great ironies of populism that it is extremely bad at dealing with people. Instead, it mobilises and weaponises irrational sentiment, and thickens the venom of ancestral prejudice. As William Galston puts it in his recent book Anti-Pluralism: “Populism is unambiguously and unashamedly tribal ... the dyad of same and different gives way to the dyad of friends and enemies.” An even sharper irony is the fact that developed societies will soon be needing more migrants, not fewer: if you doubt me, consult the work of the Italian academic Manlio Graziano on the economic idiocy of the contemporary obsession with border-strengthening.

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Inadvertently or otherwise, all this is etched into the digital mayhem of Sicario 2. Though many will enjoy it as an upscale shoot ’em up thriller, it is also a text for our times. It reflects with unnerving accuracy the sheer volatility of the age, the hectic forces of a globalised world, and the human cost of cheap political slogans.

But isn’t it just a movie? Perhaps – but only if you disregard the capacity of art and culture to fill in the gaps left by formal public discourse.

In a famous line from the first Sicario, del Toro’s character warns that “this is a land of wolves now”. Is that judgment even more apt today, I asked him – as nativism sweeps Europe, Italy targets Roma people, antisemitism creeps towards the political mainstream, social media drives us into echo chambers of digital prejudice, and the president of the United States is showing precisely what he meant by the slogan “America first”. Have we lurched deeper into the “land of wolves” and is there much hope of escape? The actor grinned, and declared himself a pessimist of the intellect but an “optimist of the will”. Right now, that strikes me as the best available starting place.

• Matthew d’Ancona is a Guardian columnist