Hunger is a savage portrait of the martyrdom to his cause of the hunger striker Bobby Sands in 1981, and a distressingly raw account about the republican “dirty protest” in the Maze prison. What makes it such a controversial watch is that it’s shot like a piece of art by a black, Turner prize winning artist whose best-known film is a Buster Keaton sketch in which the front of a barn falls on top of his motionless figure but misses.

Steve McQueen uses his first major feature to take artistic licence to the very edge. His chilling drama about the stand-off between the IRA prisoners in Long Kesh and Her Majesty’s Prison Service – co-written with Enda Walsh – is as formal as it is intense. The film opens in the home of a prison guard (Stuart Graham) as he washes his scabbed and scarred knuckles in the bathroom sink. Small clues like this silently crisscross to paint a complex picture of the brutality of life in Long Kesh. Our first taste of prison is through the frightened eyes of Davey Gillen (Brian Milligan), who is processed like a piece of meat. The ripe squalor of the “dirty protest”, where unshaved prisoners live in freezing cells covered in swirls of excrement and puddles of urine is unspeakably grim. Indeed, barely a word is spoken for minutes on end.

McQueen’s unflinching camera frames every scene like a painting. His film’s power is harnessed to one of the most hardcore pieces of Method acting I’ve ever seen. Michael Fassbender’s performance as Bobby Sands is searing and scary. The actor spent three months starving himself to chart the emaciation of Sands as he withered from pitbull health into skeletal coma. The sheer courage of this performance has the highest honours tattooed all over it. It transforms the artistic, near-silent formality of the film into a controversial and provocative act of remembering.

The heart of the film is a 23-minute, single-take camera shot of the argument between Sands and a priest (Liam Cunningham) about the political and moral danger of going on hunger strike. Sands believed not just that he could make a difference, but that he was the difference. Cunningham argues the futility and waste of this “gesture”. This scene, shot side-on in a bare smoky room, is grim and exhilarating theatre.

What makes Hunger so fresh is the eerie lack of conventional cinema rules. A corridor full of excited riot police thumping their shields has a ghastly sense of ritual about it. The river of urine that pours from under the doors of the cells during the morning slosh-out is almost magical to look at. For many viewers, the ugly realism and the abstract art are as compatible as vinegar and water. This is the black joke. The film raises troubling issues, not least should actors such as Fassbender be allowed to do this to themselves in the name of art? Exactly the kind of question that great films – and festivals – should ask.

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