With warmth and heartfelt passion, and a quintet of outstanding performances from young actors shot in looming closeup for so much of the time, Clio Barnard has created an absorbing and moving social-realist picture. It’s a film whose mix of poignancy, defiance and contaminated euphoria stayed with me hours after the closing credits.

It is about five young people from Birmingham who grew up together, reaching the end of their 20s, sensing a looming crisis and on the verge of a tragedy that is mysteriously growing from within their own increasing disparity. It is adapted by screenwriter Enda Walsh from the novel of the same name by Kieran Goddard, the statically rendered pentaptych of five consciousnesses in Goddard’s book being transformed into a fraught and dynamic home town drama with a sense memory of Fellini’s I Vitelloni.

We are introduced to our five musketeers at a boozy and weed-and-coke fuelled birthday party where the good times are laced with a suspicion that the party is actually now over. First among equals is Rian, played by Joe Cole, the one from their friend-group who has made something of himself. Using an inheritance from his late father, Rian hit the jackpot dealing in stock warrants online and while his mates are living modestly or in squalor, he has now bought a chilly and soulless designer flat in London where he dates a beautiful young woman that his friends nickname “Kate Middleton”. He isn’t really happy there and is only too glad to get back to the home turf.

Rian’s success has sent eddies of unease and self-examination through everyone else. Conor (Daryl McCormack) is the son of a builder who took pride in his work, and has been inspired by Rian’s triumph to set up a building firm in which he has persuaded Rian to be the chief investor; he is a hardworking guy and an expectant father but clearly careworn by the responsibility. Shiv (Lola Petticrew) is a smart and caring mother to two little girls, perfectly happy with her stay-at-home existence and married to Patrick (Anthony Boyle), who is deeply depressed at still being a food delivery cyclist at the end of his 20s. But easily the biggest loser – apparently – among them is Oli (Jay Lycurgo), a goofy, smiley slacker who deals heroin but is evidently inspired to change his ways by adopting a stray dog in the street; Conor sentimentally hires Oli as a site-worker.

Patrick talks about the time when he was away from them all at uni, something that makes his current lowly Deliveroo-type job even more mortifying, and he rants at the way that capitalism and the asset-owning classes are exploiting working people like him. As it happens, though, Patrick isn’t the only one with an education. Conor has named his new building firm “Dedalus” after the architect of Greek myth; this is a tribute to his dad, although Barnard may intend audiences to remember that Dedalus’s son was Icarus, who flew too close to the sun. The action is interspersed with time-lapse security footage of the Dedalus apartment block rising from the wasteground.

The film suggests that building and housing are a mythic centre to their five lives. It’s the centre also of a revived debate: is housing a social right or a maturing capital asset and loan security for the well-off? The demolition of Birmingham’s brutalist tower blocks when they were kids was a spectacular, formative event. Oli dreamily says that Satan’s face was discernible in the giant dust cloud; it was awe-inspiring, exciting, unsettling. Was it a new beginning? For Rian and Conor, the answer would appear to be yes, but Patrick is furious that their glitzy, gentrified construction venture is another money-making scheme for the newly rich. But what drives Rian anyway? Does Shiv know something about his secret Rosebud of unhappiness? What would have happened if Rian hadn’t got rich? If he hadn’t, Conor wouldn’t have been in a position to start his construction firm, and Rian wouldn’t have inadvertently encouraged him to believe it was as easily profitable as the online trading casino.

The divisions between Rian and Patrick and Patrick and Shiv might not have opened up the way they did, but then Oli’s life would not have turned around either. This is such a sad, sweet film, finally laced with sobriety and hope.