The formula of a prison film is so well-worn that any time one can really stand out from the pack, it really makes you sit up and pay attention. Starred Up, which debuts in limited release in America today, is a clankingly violent, brutal look at life inside a rough English prison, but when watching, it’s impossible to look away, no matter how brutal it gets. Centered on a violent young offender (Jack O’Connell) who’s been transferred to real prison from youth detention before he’s 21 (the titular act of being “starred up”), the film works mightily to explore prison culture while avoiding the genre’s clichés.

And they’re tough to avoid. Eric (O’Connell) is now in the same wing as his father Neville (Ben Mendelsohn, an Australian actor best known for Animal Kingdom) so there’s plenty of issues of abandonment and misdirected masculine energy to sort through. Eric also gets roped into a behavioral therapy group led by Oliver (Rupert Friend), edgy and angry in his own introverted way. Starred Up, written by Jonathan Asser and based on his experiences as a voluntary therapist in London’s Wandsworth Prison, deftly avoids any traditional plot motion. Even when progress is being made, the atmosphere crackles with the potential of it all being undone by a perceived insult or tossed-off epithet, and the speed at which things can erupt into violence.

Starred Up is easily the greatest work produced by until-now middling Scottish indie director David Mackenzie, who made his biggest impression in 2003 with Young Adam, which starred Ewan McGregor and Tilda Swinton and at least nailed the misanthropic, sub-Camus mood it was going for. Mackenzie is a director who has always had an eye for stark visuals but Starred Up is a great leap forward for him, and it succeeds partly on the back of O’Connell, a great young talent who gives the kind of performance you just can’t shake off as you exit the theater.

Watch out for O’Connell—he’s the star of Angelina Jolie’s prisoner of war drama Unbroken, which comes out this Christmas, and if his work here as Eric Love is anything to go by, he’ll be all over our screens for years to come. Eric is an immediately sympathetic figure—we enter the prison with him on his first day as he’s subjected to the usual strip-search and cold-shouldered frog-marching by the prison guards. But then, immediately upon being put in his cell, he takes apart his toothbrush and razor to make a weapon, and within the first act he’s battering riot-gear police with table legs as his reputation heads quickly south.

Eric is no prisoner with a heart of gold, nor is he some secret genius wronged by an unfeeling father. At best, you can argue that he didn’t have a chance given his circumstances, and Oliver’s approach in therapy is not to flesh out Eric’s societal problems but merely manage his anger and his default approach to problem-solving, which is to resort to hyperactive displays of masculinity and violence. As is unavoidable with any prison drama, Mackenzie is seeking to understand how all this explosive male energy can co-exist under such brutal conditions, and the answer is with great difficulty.

Any progress that Oliver makes with Eric in the group therapy feels tenuous but powerful, but there’s mounting fear that things will be dashed the second someone gets on Eric’s bad side, particularly his Neville, who is at once brooding and childlike, jealous that anyone else would pay attention to his son but completely lacking in any kind of fatherly faculties. O’Connell and Mendelsohn bounce off of each other brilliantly, while Friend has to do quieter, more introverted work as he tries to contain everyone’s testosterone and work within a system that gives him no institutional support.

Starred Up has a slightly more conventional-feeling third act, as things go sour both within the cell block and with the nasty higher-ups in charge, but it earns the charged emotions thanks to its unsparing approach to violence and its three lead performances. O’Connell, in particular, is doing that rare work that seems bereft of manipulation; he is never trying to present Eric with sympathy, rather with honesty, and in a few years when he’s the lead of some major Hollywood franchise, watching him in Starred Up will feel all the more worthwhile. Get a head-start on his bright future now while you can.