Misha Glenny and guests discuss one of the wonders of the natural world. In 1875 in the western Pacific, the crew of HMS Challenger discovered the Mariana Trench which turned out to be deeper than Everest is high, by two kilometres. Trenches like Mariana form when one tectonic plate slips under another and heads down and there are around fifty of them globally. While at one time some thought it was too dark and deep for life there and others wildly imagined monsters, the truth has turned out to be much more surprising.

Is defence of the petrol car and liberated motoring becoming the new battleground for Europe’s populist parties? Chris Bowlby visits one of the homes of German car culture and a populist stronghold, Zwickau, to see how motoring is rising up the German agenda. Is Zwickau a foretaste of something affecting all of Germany – a car-loving, car-manufacturing powerhouse in the past, now wondering anxiously what the future holds against the emergence of Chinese electric cars. And less than a hundred miles from Zwickau, just across the border in the Czech Republic, a new coalition government has recently taken power, including ministers from a populist party called Motorists for Themselves – muscular defenders of the old petrol car.

This episode of The Documentary comes to you from Assignment, investigations and journeys into the heart of global events.

*** This programme contains scenes of a sexual nature and discussion of sexual assault, including child sex abuse *** Neha Vyaso is one of the most successful intimacy co-ordinators in Bollywood. She has worked with some of Bollywood's biggest names, including actors Tiger Shroff, Deepika Padukone and Konkona Sen Sharma, and directors like Hansal Mehta. Having worked on more than 50 projects for clients including Netflix, Amazon and Tinder, she is reshaping how sex and desire is shown on screen - and how it is filmed. We join her in a workshop with two actors, who are getting comfortable with each other, their roles, and the techniques of consent and conversation that Neha is an advocate of. As they work on the choreography of their sex scene, Neha articulates how it’s a fine balance between the demands of a script, a director's vision, a character's emotional arc, and what an actor can consent to.

China is installing solar panels and wind turbines so fast that its greenhouse gases emissions may now have peaked. If this trend is confirmed, it would be a major milestone in the fight against climate change because China is the world's largest polluter. The BBC’s Beijing Correspondent Laura Bicker has travelled across China to see the country’s clean energy revolution first hand. She’s visited solar farms in the deserts of Inner Mongolia and in the tea plantations of Yunnan. Laura even discovered a huge lake with panels floating on the surface!