JOHANNESBURG — The first edition of the Joburg Film Festival will open Oct. 28 with the world premiere of “Mandela’s Gun,” a long-awaited portrait of an untold chapter in the life of the South African icon.

Directed by John Irvin, pic is a documentary-thriller hybrid that tells the story of the pistol Ethiopian emperor Haile Selassie gave Nelson Mandela as the young freedom-fighter decided to take up arms in the South African liberation struggle.

Producer Moroba Nkawe says the long process of bringing the story to the screen mirrors the remarkable, pan-African trip Mandela himself took in 1962.

“The film has…grown tremendously from the time we began filming,” she says. “As we uncovered more information through research, the story grew and…led us to film across the African continent, as we tried to bring to life this amazing, untold journey.”

She adds, “We’re extremely delighted to have the film finally ready for the public…and find it fitting that its world premiere is here in Africa.”

South African thesp Tumisho Masha plays Mandela during a forgotten chapter in his life, when the young revolutionary was tasked with building an army before he’d even learned to fire a gun. Traveling on false passports, he left South Africa to receive military training in Algeria and Ethiopia, dodging captors and would-be assassins during a far-flung African odyssey that would also take him to Botswana and Tanzania.

Shooting on-location in five African countries, as well as the U.K., added another layer of authenticity to the film, while requiring “immense support from South Africa, and also governments across the continent,” according to Nkawe.

“The commitment to tell this story, and the amazing people who supported the film, made the journey worth taking,” she says.

“Not only were we rediscovering Mandela’s journey and a part of our history that is seldom spoken about, but also learning what a huge debt South Africa owes to the African continent for the support they gave in our liberation struggle.”

Pic features never-before-seen interviews and rare archival footage from the early days of the liberation struggle. It also digs into the CIA’s role in Mandela’s arrest and imprisonment, featuring exclusive testimony from a former CIA agent.

Despite its focus on the past, Nkawe says “Mandela’s Gun” still has relevance at a time when South Africa has been roiled by political, economic and social unrest.

“As South Africans, we find ourselves and society fighting for a different kind of freedom,” says the producer. “The film…highlights that a society’s struggle for liberation is ongoing, and it’s important for us to take lessons from our former liberation leaders in fighting our struggles of today.”

For Irwin, casting a local in the lead role was crucial to the film’s success, coming on the heels of countless portrayals of the South African icon by foreign stars.

“I was not prepared to make the film unless there were South African actors playing the South African heroes that the film depicts,” he says. “It was an essential element to the historic and cultural accuracy of the film.”

Masha tops an impressive local cast that includes Zethu Dlomo, Nick Boraine, Meren Reddy, and Desmond Dube. Co-written by Malcolm Purkey and Athos Kyriakides, it was shot by cinematographer Lance Gewer, who lensed Oscar-winner “Tsotsi,” and features a soundtrack by acclaimed South African jazz musician Abdullah Ibrahim.

Director Irvin is best known for the BAFTA-winning TV series “Tinker Tailor Soldier Spy,” starring Alec Guinness; “The Dogs of War,” with Christopher Walken; and “Hamburger Hill,” with Don Cheadle and Dylan McDermott.

The first Joburg Film Fest runs Oct. 28-Nov. 5.