The film is a semi-biographical story based on the experiences of former prison guard Ronnie Thompson who spent seven years working in some of the UK's most dangerous prisons.
The reactionary result should please Daily Mail readers, if not fans of credible characters and non-risible plotting.
D’Arcy and Harper excel and there's the odd punch packed, but otherwise it's an identity parade of prison clichés you've seen a thousand times.
Some of the supporting performances are misdemeanours in themselves. But it’s got a lot of swagger, it rattles along, and there are decent turns.
This macho thriller throws a lot of punches at the prison service; how many of them connect is a different story.
Sometimes you get the authentic whiff of the criminal underclass, but it needs a stronger narrative to help it carry.
A spiky, if familiar, prison drama based on a true story.
The cast – including Noel Clarke as cocky crime kingpin Truman – scowl in all the right places, but as the grim action unfolds and the pressures of the job send D'Arcy's Sam into a predictably awful downward spiral, the film, ironically, becomes imprisoned in its own attempts to break free of convention.
Indeed, everything is too extreme. But there's a core of honesty here.
There is such an abundance of testosterone, macho posturing and flying fists here that it all becomes a bit laughable.
General release. Check local listings for show times.