A Prophet (18)

Jacques Audiard is a film-maker who understands the dramatic – and sometimes comic – thrills of self-invention. In A Self-Made Hero (1996) Mathieu Kassowitz played a man who counterfeited a glorious past as a Resistance fighter. In Read My Lips (2001) a put-upon secretary turns her deafness to account in an elaborate plan to rip off her boss. In The Beat That My Heart Skipped (2005) a small-time Parisian hoodlum puts aside his thuggish tendencies to explore his potential as a classical pianist. Audiard's characters are schemers and strivers: by dint of graft, wit and endurance they make a journey of transformation before our eyes. It is precisely what great drama should be about.

Malik El Djebena, the Arab teen protagonist of his latest film, A Prophet, faces the toughest trial yet: a Darwinian struggle for survival inside a brutal French prison. Sent down for six years, 19-year-old Malik can't read or write, hasn't a family on the outside nor a friend on the inside, and on his first day in jail is violently mugged for his trainers. If only that was the worst of it. We don't know what crime Malik was sentenced for, but it obviously wasn't murder, because he almost combusts with panic when the prison's Corsican gang boss Cesar Luciani (Niels Arestrup) coerces him into bumping off an Arab inmate who is due to testify against his interests. "I can't kill anyone," Malik mutters forlornly to himself – but he must, and soon, otherwise they are going to kill him.

His dilemma is as bleak as can be, and his crash-course in how he solves it makes the first 40 minutes of the film almost unbearably tense. The mechanics of how the would-be assassin should hide his razor-blade, and when he should make his deadly thrust into the jugular, are explained in intimate and appalling detail. The deed itself is one of the nastiest and bloodiest I can recall in recent cinema. What's odd about the film – what interrupts its otherwise downbeat mood of documentary realism – is that the murder victim, Reyeb (Hichem Yacoubi), appears more often post-mortem than he did in actual human form. His unearthly presence will determine the entire moral shape of A Prophet. Is Reyeb a protective ghost or the manifestation of Malik's unquiet conscience? We find out, though not before we have witnessed the latter's comprehensive self-education in how to get ahead.

At the heart of Malik's problem is race. The Corsican thugs for whom he works despise him as "a dirty Arab", while his own dark-skinned neighbours disdain him for a Corsican turncoat. Caught dangerously between them, Malik starts from scratch – he learns to read and write – and gradually picks up the Italian slang of Cesar and his cronies. Little by little he hauls himself up the jailbird ladder of influence, earning the perks of a fridge and a TV in his cell, keeping his eyes and ears open for the boss, before finally securing his confidence. Allowed an occasional day pass from prison, Malik pursues Corsican "business" while on the sly he launches his own fiefdom of drug-dealing in cahoots with an ex-prison friend. The worm is turning.

The story of this parallel rise and fall is superbly embodied in two major performances. Tahar Rahim, a sweet-faced newcomer, lends an astonishing sense of wary reserve to Malik, pale with fear to begin, feral in that defining act of his prison life, and later perfectly unreadable as he plays both ends of the equation from the middle. Watching him, you feel the subtle pressure of the film's scepticism about the French prison system: it is turning a genuinely resourceful young man into a career criminal. Niels Arestrup, the racketeer father in The Beat That My Heart Skipped, is entertainingly hateful as the ageing capo Cesar, the sort of man who would be called a father figure if only he had anything approximating to paternal warmth. He gives his protégé a vicious smack just for being cleverer than he ever suspected. Never having met a crime-boss lifer I can't vouch for the authenticity, but I imagine that Arestrup's impersonation nails the type pretty convincingly.

The film makes light work of its two-and-a-half hour length, though it perhaps takes some wrong turnings. Quite out of the blue Audiard and his co-writer, Thomas Bidegain, introduce a mystical element into Malik's charmed life; it refers to the film's title, though it upstages a taut encounter with an Arab crimelord that was just about to get interesting. This diversion might be accounted for by the script's origins in another screenplay by Abdel Raouf Dafri and Nicolas Peufaillit. If the denouement isn't easy to unpick it is nevertheless as suffocating as a mafioso's garotte. A Prophet will be bracketed in years to come as a prison drama, but it will stay in the memory of those who see it as a character study, bristling with cross-currents of feeling and sharp observation. A startling example, near the end: as Malik passes through airport security and submits to being frisked, he inadvertently opens his mouth wide, a prison habit to show that he's not hiding anything in there. It's a comic touch, yet also a tragic echo, for this was exactly where Malik secreted the razor-blade that first cut him adrift from his own humanity.