The fourth episode starts off with the two riding through Santa Cruz, Argentina. The plan is to cross over into Chile and then going up into the Andes. Ewan and Charley head through Argentina’s red rock landscape while a member of their team copes with altitude sickness. The duo are well and truly underway and the first signs of all are well is how well the Harleys hold up in challenging conditions. The roads alternate between unforgiving and pleasant and these e-bikes push through effortlessly. As they ride through Chilean Andes, the audience is shown a picturesque view of the beauty of the countryside, an experience which Boorman calls 'magical.'

The written word is so important in everyday life that there can be few more radical acts than forcing an entire nation to learn a new script. Yet that is what happened in Turkey in 1928 when Mustafa Kemal decreed that the Arabic script would be replaced by the letters of the Latin alphabet. Communication with computers using human language is usually made with Latin letters. This is how most Chinese people interact with their computers and smart phones, using a Latin-based phonetic script called Pinyin. As a result, even highly educated Chinese are losing the ability to write using Chinese characters. Could what is happening in China be the future of writing everywhere?

Ewan McGregor and Charley Boorman, after more than a decade since their last motorbike adventure around the world, will cover 13,000 miles over 100 days through 13 countries. Starting from the city of Ushuaia at the tip of South America, Ewan and Charley travel through the glorious and underexposed landscapes of South and Central America to Los Angeles in the United States in their most challenging expedition to date. In their journey they will use cutting-edge technology on the backs of their prototype electric Harley-Davidsons in order to contribute to the sustainability of the planet.
In the first episode, Ewan McGregor reunites with his best friend Charley Boorman to evaluate what's important in their lives, following a life-threatening accident of Charley.

How can we cope with the tricky coronavirus now rampant worldwide? As the pandemic tightens its grip on the world, there are important unanswered questions about this novel virus: Why does this infection spread so rapidly from people with no symptoms? Why do some people become critical while others don't? Will a definitive treatment be found? The underlying key to these questions lie in our immune system. Immune cells are microscopic warriors, combating viruses and another pathogens.
Through the high-tech 'eyes' of next-generation microscopes and computer-generated imagery, we will see how our immune defense corps combat against microbes and what mechanism is expected to help develop treatment.

The last episode of the series talks about the most important city in the States. Stories that go from the early 40s until today. Interviews with Rick Rubin, Emmylou, Chris Martin, LL Cool J and Barack Obama. And a real statement about what is happening with the studios business nowadays. The song 'I Am A River' is recorded during this episode.

In 1799, the German scientist Alexander von Humboldt embarked on a perilous journey of discovery across South America. It would take him to the deepest jungle near the Orinoco and to the heights of the Andes. His aim was twofold: to conduct the first scientific survey of South America and to discover how the natural world actually works — at a time when most scientists believed that the world was created less than 6,000 years ago. He later became a leading scientific figure and champion of the abolitionist movement in the US.
This extremely visual docudrama follows Humboldt’s extraordinary path. Travelling in Humboldt’s footsteps is historian Andrea Wulf, whose book on Humboldt became a worldwide bestseller. For good reason, since Humboldt’s ideas on the planet’s fragile web of life are as important today as they were 220 years ago.