Tahar Rahim on why his character in The Mauritanian is a 'lifetime lesson'

Reality, Tahar Rahim reminds us, is often stranger than fiction — especially in the case of the disturbing true story behind his new film, The Mauritanian.

Director Kevin Macdonald's sobering post-9/11 legal drama (out March 2 on premium VOD) follows a pair of attorneys (played by Jodie Foster and Shailene Woodley) who uncover a conspiracy in the treatment of Mohamedou Ould Slahi (Rahim), a suspect in the terrorist attacks who's been held for years, uncharged, as a prisoner at Guantánamo Bay. Slahi's best-selling account of his ordeal, Guantánamo Diary, formed the basis of the film; he never lost hope, even as his book describes horrific experiences of torture. "You can't imagine how impressive it is to meet this man, when you know what happened to him," Rahim, 39, tells EW. "He is a lifetime lesson."

The demanding role — which earned him a Golden Globe nomination for Best Actor in a Drama — ought to bring more attention from U.S. audiences to Rahim, whose decorated global career includes a César award for 2009's A Prophet. To prepare for The Mauritanian, the multilingual French actor lost more than 20 pounds and added two new languages to his repertoire: Hassaniya Arabic and Classical Arabic. He had the props team get him real shackles and asked that his cell be kept as cold as possible while he was sprayed with water and force-fed. "It was very, very difficult," he says. "But at the same time, putting yourself in this position helps you to reach an emotional space that you would never be able to reach if you don't put yourself in those conditions."

To help get to the core of who the man himself is, Rahim spoke with Slahi both virtually and on set. "We talked about everything. When you meet this man, the light that is coming out of him shines through the screen," Rahim recalls. "He was so, so cool. He was cracking jokes, funny, and smiling all the time, [so much so] that I couldn't even believe that he's been through this hell. It's like, how did he become like this? How can you reach this? And I think for me that was the most difficult thing to reach as a human being."

Given the film's heavy subject matter and inherently political nature, Rahim admits he was "a bit reluctant" to sign on at first. Ultimately, it was the involvement of Macdonald, with whom he collaborated on the 2011 film The Eagle, and the script that convinced him. "It's more of a humanistic movie, because this story, what happened to Mohamedou, could happen to anyone else in another context and it would be the same movie because it's about injustice," he says. "It's about a human being that is exceptional, and what he's learned through the course of his redemption."

Slahi was released and returned to his native Mauritania after 14 years in prison. But to this day, he's still close friends with one of his guards. This unlikely reality stuck with Rahim, and the actor hopes it resonates with others. "I couldn't really understand how you could turn anger into forgiveness [after] you got through this," he says. "But I'd like the audience… to know that a man like this exists, and to pick love over anger, and to pick forgiveness over doubts and fear."

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(Video courtesy of STX Films)

Related content:

• Tahar Rahim on the importance of his surprise Best Actor Golden Globe nomination
• Read EW's review of The Mauritanian