All historical dramas are about the present. The stories we choose to tell say something about the moment of the retelling, they reveal our cultural preoccupations – the stuff that keeps us up at night. The 1967 “Hotel Algiers incident” in which racist police officers responded to the firing of a starter pistol during the Motor City’s race riots using harassment and murder,  shooting several black men inside (it’s suggested because they were found in the company of two nice white middle class girls from Ohio), is an ugly, monstrous chapter in the US civil rights story that would be affecting whenever it was told. But in 2017, fifty years after the horrors depicted, the release follows a long series of reports detailing trigger happy white police officers murdering blacks across the US.

The fear-loaded, dehumanising, homicidal imperative dramatized here remains, the apparent recruiting qualification for large swathes of the American Law Enforcement Community; thugs who enjoy the privilege of being licenced bullies and unmasked vigilantes spurred on by Michael Winner movies. Detroit even manages, with remarkable prescience, to anticipate the recent Charlotteville white supremacist uprising and their apologist, Donald Trump.

Trump’s rise to power, partially on the back of an undeliverable pledge to restore the blue collar factory jobs once the bedrock of the eponymous city’s economy, here part of the film’s background milieu (it’s an important corrective to misinformed cultural nostalgia), is the orange elephant in the Algiers hotel room. With the timeframe of 50 years past firmly in mind, one watches the scenes featuring assorted aspirational black youth – a war veteran and singer with an upcoming Motown group amongst them – enjoying the company of white women in an environment which, contrary to the war zone outside, is inclusive, integrated and free loving, and wonders how a generation reviled by social division, of the kind represented here, ended up as the Trump voters of 2016.

“This is 1967” says the Ohio hairdresser to Will Poulter’s racist beat cop; the inference that his brand of unreconstructed hatred is already considered passé in some quarters. And that, not the stomach turning racism, fascistic violence and judicial whitewashing, is what stays with you long after Kathryn Bigelow’s long but gripping piece of vérité filmmaking has ended. It’s the knowledge that ’67 wasn’t a turning point, just a staging post. It’s the knowledge America would be there again, with 1992’s L.A Riots, with mass incarceration. America, it seems, never learns, refusing to evolve, addicted to its founding injustices. Little wonder that Gore Vidal once refused to name the American Century, opting instead for the “19^th but one”. Nothing, he thought, had been achieved, the potential wasted.

Bigelow’s gripping narrative offers a few hints at what might have gone wrong. The fate of John Boyega’s character is instructive, as is suggests that any black figure in authority received short shrift from the community, labelled “an Uncle Tom”. A black congressman, pleading for restraint, is similarly dismissed by the crowd. A reluctance to enter politics and policing – an understandable reaction to being persecuted by that majority white elite, is a formula for keeping those institutions unrepresentative and sustained by lack of empathy for those under the cosh.

The decision of one survivor, to abandon a promising music career because of a newly formed hatred of white people, “I ain’t singing so some white motherfuckers can dance” – hints at a self-segregating tendency, that suits, perhaps emboldens, Trump’s America. The movie paints a picture of institutional corruption, division and the legacy of white flight and persecution with great intimacy and an eye for character detail. The question it leaves you with is, what progress?