The bombing of Hiroshima, a single weapon equal to 20,000 tons of TNT, opens this account of how the Cold War took shape in the years right after World War Two. The film moves from the founding of the United Nations, when fifty nations recently at war sign on to a peace project, to the Soviet occupation of Eastern Europe under terms the wartime allies themselves agreed to. Archival footage and testimony from people who escaped across the Iron Curtain describe secret police, torture, and executions behind the barbed wire and watchtowers dividing the continent. The narrative tracks the United States restarting atomic tests at Bikini Atoll, signaling it would use the bomb again if pushed, then follows the war's first proxy conflict in Greece, where American money and arms back the government against Soviet-backed rebels. The episode closes with Mao's communist forces defeating the US-supported Nationalist government in China, creating a second major communist power and setting the superpower rivalry that would define the following decades.