Cell 211, Daniel Monzon, 113 min (18)

A new prison guard ends up having to pretend to be one of the inmates just to stay alive in this visceral Spanish drama that makes 'Shawshank' look warm and cuddly

(PICSELECT )

The film that swept the board at the Goya Awards (the Spanish equivalent of the Baftas), Cell 211 is a far cry from The Shawshank Redemption.

Frank Darabont's prison movie pitched us into a world of violent guards, corrupt wardens and mostly harmless inmates, who queued up like docile suburbanites to have their tax affairs managed by nice Tim Robbins. Things are rather different in Zamora Provincial Prison. There, the inmates would decapitate you if you failed to pass the salt. And they'd do it in a really really horrible way if they discovered you were actually a guard masquerading as one of them. That's the threat at the heart of Daniel Monzon's superior thriller.

The film starts with the suicide of Monae, a grizzled lifer in Cell 211, who slashes his wrists after realising that nobody believes there's a tumour "the size of a kiwi fruit" growing in his head. Next morning, a new-bug prison guard called Juan (Alberto Ammann) is being shown around the cell blocks by his colleagues, who helpfully offer alarming advice about his new charges ("Always look them in the eye. Never show them you're scared.") when he is hit by a random piece of falling masonry. Bloodstained and concussed, he's carried into the now-empty Cell 211 – and abruptly abandoned by the other screws, as a full-scale riot breaks out in the prison's Extremely Angry and Derangedly Psychotic Wing.

What would you do, if surrounded by 200 guard-hating, Spanish murderers, rapists and armed robbers? Try to reason with them? Stay hunkered down in your cell? Or try to butch it out by pretending you're a new prisoner who's been bloodied by the guards? The film snaps into vivid life when Juan suddenly realises that everything he's wearing shouts his identity as an outsider, and he tries, in a frenzy, to rid himself of wallet, wedding ring, belt, shoelaces and any other prison-screw accessories.

He is taken before Malamadre ("Bad Mother"), the jail's resident Mr Nasty, and convinces him that he's a genuine crim, newly arrived and doing 19 years for homicide. But does Malamadre really believe him? Played with relish by Luis Tosar, this shaven-headed, black-bearded, caterpillar-browed, bulging-eyed, gravel-voiced tyrant is a slimmed-down version of Popeye's nemesis, Bluto. But behind his bluster lies a shrewd intelligence and black suspicion that is genuinely scary. Every time we think Juan has safely duped the felons, Malamadre narrows his terrifying eyes, mutters to his myrmidons, and we fear once again for our hero's chances of surviving evisceration.

There's nothing to stop a government Swat team from ending the riot, except for the presence, in a separate cell, of three political prisoners from the Basque ETA organisation – men held in semi-respect by the rank-and-file prisoners, because, though they're killers, they kill people at a distance, with bombs. It's politically vital their lives are not put in jeopardy, however, and they become hostages: as long as they're alive, the Spanish SAS won't come abseiling down the walls, blowing everyone to Kingdom Come.

Juan becomes a key figure in the ensuing face-off between prisoners and warders, and we watch as this once mild-mannered guard grows into a convincing, then a real, desperado. Alberto Ammann, as Juan, is extraordinarily watchable: an Iberian Adrien Brody with a long nervy face and an emotional tautness like a coiled spring, his life depends on his ability to suggest that he's capable of terminal violence; by the end of the film, however, he's no longer acting.

As the situation at the jail worsens, and the prisoners' relatives start to attack the police, Juan's pretty, pregnant wife Elena (Marta Etura) decides to get involved. So we now have riots inside and outside the wrecked building, the good guy under threat from the crazies inside, his wife being jostled by police outside. Everyone's life hangs by a thread. Juan and Malamadre develop an unlikely but just-plausible bond of friendship, even as the latter tells the former: "You won't come out of this alive." And Juan discovers himself siding with the murderers against the law-enforcing tyrants. His face suffused with hatred, his eyes blazing with indignation, he becomes their spokesman and (almost) leader, demanding justice and prisoner rights. It's quite a transformation.

At a shade under two hours, Cell 211 can at times feel like a long stretch in the Scrubs. But it's directed with ferocious energy by Monzon, the rhythms of ultra-violence and tense negotiation among the men become hypnotic, and the twists and turns of the plot (script by Jorge Guerricaechevarria) keep you on the edge of your seat throughout. Just be prepared to have the truly alarming face and mad staring eyes of Luis Tosar coming for you in dreams for several nights afterwards.