It's 20 years since the genocide in Rwanda where an estimated 800,000 people were slaughtered in just 100 days. The BBC's International Development correspondent, Mark Doyle, returns to Rwanda to piece together the remarkable story of an unsung hero of those terrible days, Captain Mbaye Diagne. Diagne, an unarmed United Nation's peacekeeper from Senegal, saved the lives of hundreds of civilians caught up in the conflict. Some of those he rescued speak about their escape for the first time in public. Show less