When James Le Mesurier fell to his death in Turkey in 2019 he left behind a tangle of truths and lies. 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.