Riots and protests have broken out in cities across the USA following the death of George Floyd after his arrest by white police officers in Minneapolis. But one black American’s impassioned plea for calm has gone viral in the midst of the violence. Atlanta-based rapper Killer Mike made an impromptu speech calling on his fellow citizens not to burn their city but to organise and mobilise and to use their votes to bring about change. Mark Coles has been speaking to people who know Killer Mike well, and finding out more about his past, his music and his life in Atlanta.