This episode examines the end of and the period immediately after World War II. It looks at Stalin's efforts to seize control of Poland and Eastern Europe, Democratic part bosses efforts to drop Henry Wallace from the 1944 presidential ticket, and British efforts to maintain their colonial holdings after the war.

What if aliens landed on Earth? Much of science fiction explores the moment of first contact – what will people do when the aliens land? From H. G. Wells’ pioneering The War of the Worlds to Independence Day, Men in Black, and District 9, Invasion deals with our fears of alien invasions of earth. David Tennant explains the appeal of Doctor Who’s Daleks and Cybermen while John Carpenter and Chris Carter explore the rich appeal of the paranoia fuelled by hidden aliens with The Thing and The X-Files. It also asks, what if the monsters were our own creation? With the aid of rarely seen animation tests, Phil Tippett takes us behind the scenes in the creation of the dinosaurs of Jurassic Park. But not all invasions are hostile. Peter Coyote and Richard Dreyfuss discuss the creation of Spielberg’s spellbinding classics E.T. the Extra-Terrestrial and Close Encounters of the Third Kind. There is more than one kind of invasion.

Andrew Graham-Dixon explores how Russia changed from a feudal nation of aristocratic excess to a hotbed of revolution at the beginning of the 20th century and how art moved from being a servant of the state to an agent of its destruction. From monuments that celebrate the absolutism of the tsars to the epic Russian landscape as inspiration; from the design and construction of gold and glittering palaces to the minutiae of diamond-encrusted Faberge eggs; and eventually to the stark and radical paintings of the avant-garde, the journey through Russian art history is one of extraordinary beauty and surprise.

The Pythagorian philosopher Plato hinted enigmatically that there was a golden key that unified all of the mysteries of the universe. It is this golden key that we will return to time and again throughout our exploration. The golden key is the intelligence of the logos, the source of the primordial om. One could say that it is the mind of God. With our limited senses we are observing only the outer manifestation of the hidden mechanics of self similarity. The source of this divine symmetry is the greatest mystery of our existence.

As Michelle's loved ones cope with her sudden death, her work to unmask the Golden State Killer lives on. After inheriting Michelle's 37 boxes of case files, Paul Haynes and Billy Jensen work alongside Patton Oswalt, to finish her book.

There is a tendency to deny German culture the equal reverence of Italy or Spain, and this enlightening new series provides a wonderful opportunity to explore a great, yet often neglected, artistic tradition whose influence has been just as profound. Andrew Graham-Dixon concludes his exploration of German art by investigating the dark and difficult times of the 20th century. Dominating the landscape is the figure of Adolf Hitler, failed artist, would-be architect and obsessed with the aesthetics of his 1,000-year Reich". In a series of extraordinary building projects and exhibitions, Hitler waged a propaganda war against every form of modern art as a prelude to unleashing total war on the whole of Europe. After the war the shadow of the Third Reich persisted, Germany remained divided and traumatised. How would artists deal with a past that everybody wanted to forget? Journeying through the work of Otto Dix and George Grosz and the age of the Bauhaus to the post-war painters Georg Baselitz, Hilla Becher and the conceptual artist Joseph Beuys is a long and strange journey, but the signs that art has a place at the heart of the new reunited Germany are clearly visible.