In April 1942, the Imperial Japanese Army captured Burma, closing the only ground route from India to China. Supplies now had to be flown over the treacherous Himalayas, on the world's most dangerous air route. This is the story of the Allied troops who braved this perilous journey, flying unreliable aircraft through monsoons and enemy fire, with primitive navigation tools. Caroline Alexander delves into memoirs and records to reveal the pilots' and soldiers' experiences and portrays the exploits of commanders like 'Vinegar Joe' Stillwell and Claire Lee Chennault.