The final episode of the series ponders the fate of planet Earth. Neil deGrasse Tyson opens with a reflection on science and those who help us understand it: 'We all feel the weight of the shadows on our future, but in another time, every bit as ominous as our own, there were those who could see a way through the darkness to find a star to steer by.'
The young Carl Sagan and Neil Tyson first discovered their passion for science at the NY World's Fairs of the past. We visit the dazzling Pavilions of the 2039 NY World's Fair, where problems we currently think intractable have been plausibly solved through public commitment and scientific imagination. And our baby is a woman now, with a baby of her own and a future bright with possibilities.

Travel writer Simon Reeve embarks upon two long-distance journeys across Turkey, exploring this dramatic and beautiful country that now finds itself at the centre of world events. In this programme, he visits Istanbul and the beaches and crystal clear waters of the Aegean Sea, before ending up at the war-torn border with Syria.
In the region thought to have been the origin of the first vineyards, Simon meets a producer now trying to sell wine in a Muslim country with an increasingly conservative government. In Istanbul, he meets some of the people shaping modern Turkey, from loyal supporters of the nation's controversial and authoritarian president to the master builder constructing one of the world's largest mosques and the notorious billionaire cashing in on a Turkish property boom.
Along Turkey's famous Turquoise Coast, Simon has a taste of luxury at the country's most expensive hotel, but discovers an industry on its knees as war in Syria and deadly terror attacks keep millions of holidaymakers away.

Did Marco Polo, the most illustrious traveller in history, ever go to China? To this day doubt lingers, among some scholars, as to whether the Venetian’s book is a personal account of China’s 13th-century Middle Kingdom and its marvels. Scientists, western scholars and Chinese historians have uncovered striking new evidence that the son of Venetian merchants actually had been to China. Explore the mysteries of the historical figure in this featured documentary.

Albert Einstein, the most famous scientist of all time, was a world-renowned celebrity, greeted like a rock star when he appeared in public. An anti-war firebrand, Einstein also spoke out on issues ranging from women's rights and racism to immigration and nuclear arms control. But today, his image has been neutered into that of a charmingly absent-minded genius. He was, in fact, a powerful force for social change and a model for political activism.
Using a wealth of rarely-seen archival footage, correspondence, and new and illuminating interviews, filmmaker Julia Newman makes the case that Albert Einstein's example of social and political activism is as important today as are his brilliant, groundbreaking theories.

A ground-breaking new trial at Imperial College London sees, for the first time ever under controlled conditions, a psychedelic drug tested head-to-head against a standard antidepressant as a treatment for depression. The film follows a pioneering team of scientists and psychotherapists as they compare the effects of psilocybin (the active ingredient of magic mushrooms) with an antidepressant on a small group of participants with clinical depression.
This is scientific research at its most cutting edge. With over seven million people being prescribed antidepressants each year in England alone, this drug trial is an important milestone in understanding a completely different treatment for depression. How do psychedelic drugs measure up against the industry-standard antidepressants that have been popular since the 1990s? The empirical results of the trial are explored alongside the participants’ powerful lived experience.

Without us noticing, modern life has been taken over. Algorithms run everything from search engines on the internet to satnavs and credit card data security - they even help us travel the world, find love and save lives. Professor Marcus du Sautoy demystifies the hidden world of algorithms. By showing us some of the algorithms most essential to our lives, he reveals where these 2,000-year-old problem solvers came from, how they work, what they have achieved and how they are now so advanced they can even programme themselves.