Forest Whitaker and Orlando Bloom helped bring the Cannes Film Festival to a close with the premiere of dark drama Zulu.
The pair play South African policeman investigating the murder of a white teenager in the violent film, which highlights gang culture in the country and the lingering effects of apartheid.
Oscar-winning actor Forest met with real-life Zulu gang members as part of his research for the film, shadowed police officers and learned to speak Zulu and Afrikaans.
He revealed: "I met the actual gang members from the different communities: the Zulu gang leaders, and the different members out of the prisons... I find that it helps to find the source of the character.
"The violent crimes unit took me around quite a bit... which helped me understand what it was like to be around the townships.
"I was dealing with officers, and people in the community were saying: 'They're not listening to us. They're not helping us. They're allowing people to do these horrible things in our neighbourhood. We have to take charge. We are the elders of this community, and we are not going to allow certain things to happen.'
"And where does all that come from? Where is the pain that brings out these things? I think that's what's going to have to be addressed."
But Forest insisted the reality is not as bleak as the film might make out. He said apartheid-related forgiveness is occurring.
He said: "Those issues which have to do partly with forgiveness and being able to move forward
"It is slow ... (but) the continent is full of potentiality, it's growing, it's changing, it's moving."