Joseph Stalin was a tyrant responsible for the death of millions - yet he was also a vital ally of Britain and America during the Second World War.How was it possible for Churchill and Roosevelt to deal with one tyrant - Stalin - in order to help beat another - Adolf Hitler? That's one of the key questions at the heart of this series.Using dramatic reconstructions, based on extensive fresh research in Russian and Western archives, and testimony from witnesses of the time, including former Soviet secret policemen who have not spoken before on camera, in order to tell a 'behind closed doors' history. It's a new way of looking at this most vital period, and may change the way people think about the war.This episode focuses on the secret history of Churchill's first meeting with Stalin in Moscow and the behind-the-scenes actions of Roosevelt's emissary to the Soviet Union.