In August 1939, a German plane touched down in Moscow and Soviet officials had to borrow a swastika flag from a film studio to greet Joachim von Ribbentrop. That borrowed flag is the perfect symbol for the Molotov-Ribbentrop Pact, an alliance of pure theater between two regimes whose ideologies demanded the destruction of the other. This episode traces how Nazi Germany and the Soviet Union went from fighting a proxy war in Spain to signing a ten-year non-aggression treaty with a secret protocol that divided Poland, the Baltic states, Finland and Bessarabia into spheres of influence.

We look at the economic logic behind the deal, the Munich Agreement that fed Stalin's paranoia about the West, the British delegation that arrived in Moscow by slow boat without credentials, and the replacement of Maxim Litvinov with Vyacheslav Molotov as a sign ...