The Cold War: 1945-1950 is the fourth episode of the documentary series. In it,Oliver Stone and his collaborators tries to examine the rise of the Soviet Union after the end of World War II and how Communism came about.

As the documentary producers provide us events on how Communism became a by word to people all over the world,it also provides us an information of the causes of the Cold War based from the narration of practically monthly events from 1945 to 1950. While it does not point out who started it,it somehow blames the United States Government particularly President Harry Truman due to the dropping of the atomic bomb in Japan and how the United States tried to stop its spread by getting involved militarily by countries like Korea and Vietnam.In addition to that,we also are informed with British Prime Minister Winston Churchill's activities particularly his Iron Curtain speech after he got re-elected into the position after the war. It also discusses the activities of the Senate particularly the House Un-American Activities Committee and the Federal Bureau of Investigation (FBI) particularly its chief J.Edgar Hoover. The conspiracies being tackled is the rise of Joseph McCarthy and how the House Un-American Activities Committee tried to investigated the role of Hollywood in the Communist propaganda.