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.

1916. The war is raging in Europe and stretches from the trenches in France to the Italian Alps and the Balkans, and beyond to the gates of the Eastern world. The conflict becomes industrial, and millions of shells rain down on the battlefields; Verdun and the Somme are the deadliest battles in this second year of the war. Who can stop this infernal machine?

The second episode tells the story of the trial of Hermann Goering, Hitler's charismatic and ruthless second-in-command. On trial for his life at Nuremberg, the unrepentant Reich Marshal turned the tables on the Allies. So much so that Chief Prosecutor Justice Robert Jackson began to wish the Allies had followed Churchill's suggestion and shot the leading Nazis out of hand. This documentary drama traces the behind-the-scenes story of Goering's attempt to re-ignite Nazism from the courtroom.

Vorenus and Pullo return to the Collegium in Rome with Vorenus' family, but some of the 'changes' that Pullo had warned him about regarding his two daughters Vorena both the Elder and Younger, as well as his wife's son, begin to manifest themselves into hostility and resentment.
But Vorenus is completely oblivious to this, and is too blissfully happy to return to the role of 'father'. Meanwhile, Octavian finally returns and manages to negotiate the Senate Consul's seat from a scheming Cicero.

Intrepid adventurer Michael Palin travels through Pakistan's North-West Frontier Province, starting on the Khyber Pass and ending five miles from K2 on the Pakistan/China border. He passes through Darra, visits a street dentist in Peshawar, goes bull racing with a Pakistani aristocrat and is almost trampled to death, and finally crosses over the Lowari Pass into the buffer state of Chitral.

The final hours of WW2 changed the course of history. As the Americans inch closer to Japan the Japanese fight with greater intensity. The question now is how to end the conflict. Starve them into capitulation? Many in US command believe the Japanese will never surrender. The alternative is to stage a massive invasion that would dwarf D-Day? The massacre of millions would be inevitable. But then a third and far darker option becomes available: the atom bomb.