Sagan discusses comets and asteroids as planetary impactors, giving recent examples of the Tunguska event and a lunar impact described by Canterbury monks in 1178. It moves to a description of the environment of Venus, from the previous fantastic theories of people such as Immanuel Velikovsky to the information gained by the Venera landers and its implications for Earth's greenhouse effect. The Cosmos Update highlights the connection to global warming.

The journeys of the Voyager probes is put in the context of the Netherlands in the seventeenth century, with a centuries-long tradition of sailing ship explorers, and its contemporary thinkers (such as Constantijn Huygens and his son Christian). Their discoveries are compared to the Voyager probes' discoveries among the Jovian and Saturn systems. In Cosmos Update, image processing reconstructs Voyager’s worlds and Voyager’s last portrait of the Solar System as it leaves is shown.

Questions are raised about the search for intelligent life beyond the Earth, with UFOs and other close encounters refuted in favor of communications through SETI and radio telescope such as the Arecibo Observatory. The probability of technically advanced civilizations existing elsewhere in the Milky Way is interpreted using the Drake equation and a future hypothetical Encyclopedia Galactica is discussed as a repository of information about other worlds in the galaxy. The Cosmos Update notes that there have been fewer sightings of UFOs and more stories of abductions, while mentioning the META scanning the skies for signals.

Until World War II, Latino immigration to the United States was overwhelmingly Mexican-American. Now three new waves bring large-scale immigration from Puerto Rico, Cuba, and the Dominican Republic. As the Puerto Rican government implements a historic overhaul over a million Puerto Ricans are encouraged to leave for the US mainland, to alleviate the economic pressure. A young Juanita Sanabria arrives in New York, works hard in the garment district, but encounters hostility and discrimination. Ethnic tensions explode in youth gang warfare depicted in films like West Side Story, etching the stereotype of the knife wielding Puerto Rican in the American consciousness.

It was the bloodiest war in history, yet Hitler's brutal invasion of the Soviet Union and Stalin's subsequent fight back is surprisingly little known in the West. More than 30 million people died during Hitler and Stalin's terrible war in the East - more than in any other single war in history. With direct testimony from people who perpetrated atrocities and the victims who suffered on both sides, we bring the unspeakable to the screen and allowing victims and aggressors to tell the truth as they see it. In the first episode, we will look at Hitler's plans to invade the Soviet Union and the horror of the first months of conflict.

Soldiers and officers continually came into conflict with their consciences. How much freedom did individuals have? Were they executing Hitler's criminal plans, or was it the Wehrmacht's war? There were crimes against humanity, against civilians, prisoners of war, and there was the Holocaust itself. The Trent Park records discovered and analysed by historian Sönke Neitzel, author of Tapping Hitler's Generals, show that the 84 German generals who were interned at Trent Park were aware of the severity of the war crimes they had been involved in and that some discussed them almost compulsively. They included the Commissar Order, to kill any Soviet commissar, and Rathenau's order to kill the Jews, including children.