Confirmed fans of prison drama will recognise the licks; friendless on the inside and disenfranchised by the outside world, 19-year-old petty crook Malik El Djebena (Tahar Rahim) has been sentenced to six years in prison, but without suitable protection he may not survive the strip searches and yard skirmishes of the first week.

When the prison’s resident Corsican gang, Cesar Luciani (The Beat That My Heart Skipped), threatens our vulnerable young hero with death unless he murders a fellow Arab inmate, Reyeb (Hichem Yacoubi), he is in no position to refuse.

Tellingly, the film was originally called ‘Gotta Serve Somebody’ after the Dylan song.

As the years pass, he ascends to Cesar’s right hand though the two men are hardly friendly. Cesar may organise day releases so that his minion can do the gang’s dirtiest jobs on the outside, but he continues to regard Malik as a “dirty Arab”, while the neighbouring jailyard Muslims see only Corsican loyalties. Perhaps, however, the Italian thug has schooled his apprentice a little too well.

Throughout, Mr. Rahim is mesmerising. His transformation from a shy, illiterate street urchin into a criminal kingpin is conveyed in deft physical movements. For the overture – a suitably visceral sequence of cavity probing and beatings - he slouches and shrinks with terrified darting eyes. Two hours into the well justified running time, he’s strutting around like John Travolta.

The actor’s sustained realism is nicely offset by the director’s keen eye for filth and fury, Juliette Welfling’s kiss kiss bang bang edits and Stephane Fontaine’s unnervingly natural cinematography. This is one of those great films that can recall others from the pantheon – Hunger, A Short Film About Killing, The Bourne Ultimatum – but its fierce quality and a supernatural subplot ensure A Prophet, appropriately enough, sounds like a lone voice calling out of the wilderness.