“The crime scene had been left unguarded for two weeks”. What really happened in the Douma massacre? This episode is a diversion from the story of the life and death of James Le Mesurier. It’s about one of the most contested events in the war - the chemical attack in the town of Douma in 2018. Unravelling what really happened there takes us to the heart of the global race to control the narrative of the Syrian war. Mayday tells the extraordinary real story of the man who organised the White Helmets – rescuers who film themselves pulling survivors from bombed out buildings in rebel-held areas of Syria – and investigates claims that, far from being heroes, they are part of a very elaborate hoax. James Le Mesurier – his detractors say – was a British secret agent, pulling the strings. So when his body was found by worshippers on their way to morning prayers, there were a lot questions. This episode contains a description of the aftermath of a chemical attack. This episode has been edited since original publication following a complaint. https://www.bbc.co.uk/contact/ecu/mayday-the-canister-on-the-bed-radio-4-20-november-2020 Produced, written and presented by Chloe Hadjimatheou Editor: Emma Rippon Researcher: Tom Wright Production Coordinator: Gemma Ashman Sound Design and Mixing by Neil Churchill With additional mixing by Graham Puddifoot and Gareth Jones Arabic translation and additional research: Vanessa Bowles, Abdul Kader Habak Turkish Researcher: Nevin Sungur Narrative Consultant: John Yorke Original music: Nick Mundy Final track Zamilou by Bu Kolthoum