We know it’s going to end badly. Genuine mobile phone footage captures the chaos and discord on the platform of the eponymous station where a bunch of lads are corralled by jittery transport police on New Year’s Eve in Oakland.

This is not a spoiler because this is not a fiction. The shooting of Oscar Grant is a truth, a cause, an outrage. Although not so well known here, in the US the death caused riots, with parallels to the Mark Duggan shooting in London.

Writer-director Ryan Coogler showcases his grip of story, tone and character with his low-key, verite style and tumbling, mumbling domesticity. Cleverly, he plays to whatever preconceptions that initial scene of white-cop-black-kid provokes and then peels away layer upon layer to reveal a more textured truth.

The film opens at the beginning of that fateful day with 22-year-old Oscar, holding a bag of weed, getting chastised for cheating on his girl Sophina (a deeply impressive Melonie Diaz). So far, so Wire. We’re braced for a cliched tale of urban deprivation, baby daddies and despair.

But Oscar is not bad. He’s no saint either. Been in prison a spell. Badmouthed his mother (a remarkable Octavia Spencer). But loves her too. Bails out his sis with her rent, no questions; gives the lowdown on fried fish to a (white) woman out her depth; spends money he hasn’t got on presents.

He’s a fallible human trying to make things work for his family, which includes four-year-old apple of his eye Tatiana.

Today January 31, 2008, he’s trying to make amends. Give up dealing. Make a fresh start. Maybe marry Sophina.

Coogler’s dramatic licence makes this a day heavy with portent – his mother’s birthday, fireworks in the city, Grant’s creeping epiphany. A dog dies on the roadway, blood in his muzzle. Tatiana mistakes firecrackers for gunshots and wants her dad to stay home.

Oscar is torn between the temptations of crime and the trials of a good man short on cash. This comes not in heavy dollops but in beautiful segments, tiny, powerful vignettes of family life – like when he plots to give his mom a white-folks birthday card as a joke.

All credit then to Wire alumni Michael B Jordan as Oscar, taking a cliche and making him fully rounded. His support cast (including Ariana Neal who plays the daughter) could be playing themselves such are the effortless dynamics and easy chemistry.

And the evening approaches. Fireworks do arrive, of all sorts. Because we know how this evening ends. And we’re waiting, waiting, waiting, sick to our stomachs because we know too much.

Tomorrow we’ll go to Chuck E Cheese, he tells his daughter. Tomorrow. Every word, gesture, smile has a poignancy that is almost too much to bear. But Oscar is so real now that we cannot look away, hoping that this time the officer will find his Taser not his gun.

Coogler begins this uncompromising and compelling film with the mobile footage that spread like wildfire across social media. He ends with another abrupt reality. A peaceful rally in memory of Oscar Grant in 2013 with little Tatiana, the real one, amid a sea of slogans and goodwill that are no kind of substitute.

At the 2013 Sundance Film Festival, this Forest Whitaker-produced movie won the Grand Jury Prize and the Audience Award although Oscar talk came to nothing.

Either way it would be hard to imagine – nor less digest – a more powerful rebuke at London this year.

Fruitvale Station
(tbc) 85mins
On general release on June 6
★★★★★

Go to sundance-london.com