Beyoncé's Grammy-winning director explores his grandfather's role in Biafran war

For 44-year-old Leke, who was born and grew up in Abeokuta, Ogun state in south-western Nigeria, it was "a line or two lines in a book".

"It's still not fully covered, you know, the extent of the suffering. And I think, for me, Nigeria is just scared to confront its own truth," he said.

Leke and his 23 siblings grew up hearing war stories from their dad, Godwin Alabi-Isama, who served as chief of staff to Brigadier Benjamin Adekunle of the 3 Marine Commando during the conflict.

"It just felt like my dad was known for helping liberate this town and these villages. I saw him as a war hero," he said.

It was not until his early 30s when Leke started to research what happened during the war that he learnt of the mass starvation in Biafra, of his father's controversial role in the conflict and the true extent of the suffering.

The federal army, including 3 Marine Commando, have faced allegations of war crimes for their conduct in Biafra, including executing civilians.

"The first time I saw those clips of people, children starved… it was horrific. And I think that was a moment of truth for me," Leke said.

"That was the moment for me where the horrors of the war then became facts. Like, OK, something really terrible happened and my dad was on the other side of it.

"When you find out that, you know, your truth is not the only truth, it was a humbling moment."

Leke and Meji said they could not understand why there were not many films about the civil war made by Nigerians, describing how difficult it was to find a truthful account of what happened.

This is one of the many reasons the duo, who usually work with international music stars, wanted to make this documentary.

"It's a topic that, you know, is whispered," said Meji, whose music video productions have played a significant role in bringing Nigeria's music scene to the world's attention, with their characteristically complex choreography and colour attracting tens of millions of online views.

"It hasn't been attacked head on and, you know, presented from an inquisitive younger generation like this before," he said.

The documentary pulls together talent from across the region - with Meji convincing Ghanaian composer Ray Michael Djan Jr, who worked on the soundtrack for Black Panther: Wakanda Forever, to do the music.

It also relied on the expertise of the BBC's Igbo service, Igbo historians and features first-hand accounts from survivors, some of whom have never spoken publicly about their trauma before.

"This generation is slowly fading, and if we do not preserve their testimonies now, we risk losing not only their memories, but the chance to fully document this history in a way that can contribute to understanding and healing," said Leke.

Two of the central characters are former female soldiers, who fought on opposite sides. There are also interviews with an aid worker and former BBC correspondent Martin Bell, who both voice criticism about the international response to the crisis.

While Leke and Meji had heard many war stories from Godwin Alabi-Isama before, they had never been in a position to ask the tough questions.

The BBC editorial team led the interview to ensure the former commander was pushed on the war crime allegations made against 3 Marine Commando.

During the conflict, the Nigerian government also blocked food from entering Biafra - cutting the region's access to seaports, airfields and foreign supplies.

The blockade led to famine and it is thought starvation is how hundreds of thousands of people died.

Leke described the moment where he showed his dad the black-and-white footage of emaciated children and said until then in his "43 years of existence" he had never heard his father's voice shake.

"Even every time I watch it back, when it gets to that point, I get, goosebumps," he said.

During the interview his father also described how, unbeknown to him at the time of the conflict, he ate human flesh. The moment of cannibalism happened when his unit was served food by villagers in occupied Biafran territory.

In response to the forthcoming documentary, Nigeria's government said it hoped it would serve as a reminder of how far the country had come in the last 59 years "and of the enduring importance of dialogue, reconciliation and shared purpose in building a stronger nation for generations to come".

Both Leke and Meji would like that - and more.

"My hope is that this film encourages Nigerians to confront the darker parts of our shared history with honesty, reflection, and empathy," said Leke.

Meji agrees: "We really hope this documentary encourages more survivors to tell their stories and document our history further. It's up to us to do it."

Additional reporting by Charlie Northcott, Izzy Fleming and Adline Okere

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