On April 7, 2018, the Syrian town of Douma, on the outskirts of the capital Damascus, was targeted by a chemical attack. Evidence pointed to the Syrian regime, yet proof vanished, and eyewitnesses went silent. Eight years later, FRANCE 24's Jenna Le Bras tracked down survivors and witnesses of the deadly attack. She also met representatives of some of the world's most powerful institutions to understand how a massive cover-up campaign had been orchestrated by the regime, with Russian support.