For the past five years an undercover network of Rohingya activists have been risking their lives to secretly film evidence of years of repression, violence and mass murder by the Myanmar authorities. This Dispatches special has been given exclusive access to hundreds of their videos and the first-ever interview with the network to provide the most complete account of how ethnic tension degenerated into what some are calling state-sanctioned genocide, with reporter Evan Williams asking whether Myanmar's leaders be held accountable for the atrocities.