The film stars Tahar Rahim in the title role as an imprisoned petty criminal of Algerian origin who rises in the prison hierarchy, becoming a mob associate and drug trafficker as he is absorbed into the Corsican mafia and then ingratiates himself into the Maghrebi crime syndicate.

Alone and illiterate upon his arrival, he falls under the sway of Corsican mobsters, led by César Luciani, who enforces a brutal rule.

When Luciani forces him to be the unwilling assassin of Reyeb, a Maghrebi witness in a trial, Malik gains the protection of the Corsicans despite his North African origin.

When Ryad gains an early release due to testicular cancer, the three partners organize a drug-running enterprise to sell hashish.

Malik is sent to meet Brahim Lattrache in Marseille, another Maghrebi, who is involved in a deal between Luciani and the Lingherris, an Italian mafia group.

Luciani believes there is a "mole" in his organization and decides to use Malik to assassinate Jacky Marcaggi, the don of the Corsican mafia, for secretly dealing with the Lingherris.

But Malik and Ryad have their own plan for Marcaggi: they kill his bodyguards, kidnap him, and inform him that it was Luciani who ordered the hit before abandoning him in the city.

[4][5] Audiard cast Niels Arestrup as the Corsican crime boss César Luciani, after featuring him in his previous film, The Beat that My Heart Skipped.

Its critical consensus states that "Featuring an impressive star turn by newcomer Tahar Rahim, A Prophet is a French gangster film filled with arresting, immediate details.

[4] Jonathan Romney of Screen International said that the film "works both as hard-edged, painstaking detailed social realism and as a compelling genre entertainment".

Davies described the film's main achievement as conveying a character as "someone we care about and gun for", who started life on screen as a blank slate.

The other four films in the category were Ajami, The Milk of Sorrow and The White Ribbon, and the eventual winner, El secreto de sus ojos.

[20] Actors Sam Claflin, Karl Urban and Jon Bernthal and filmmakers Judd Apatow and Ryan Coogler named it as one of their favourite films.

[22] On 22 January 2016, Deadline reported that Sam Raimi was in talks to direct Sony's remake of the film, with Neal H. Moritz and Tobe Jaffe producing, and Dennis Lehane writing the script.

[23] On February 14, 2020, it was reported that Paramount Players acquired the project, which became Rapman’s American Son with Stephan James and Russell Crowe.