Professor Iain Stewart continues his epic exploration of how the planet has shaped human history. Iain explores the most recently established force, humans. It's easy to think of the human impact on the planet as a negative one, but as he discovers, this isn't always the case. It is clear that humans have unprecedented control over many of the planet's geological cycles; the question is, how will the human race use this power?

Professor Iain Stewart continues his epic exploration of how the planet has shaped human history. Iain explores man's relationship with fire. He begins by embarking on an extraordinary encounter with this terrifying force of nature - a walk right through the heart of a raging fire. Fire has long been our main source of energy and Iain shows how this meant that the planet played a crucial role in Britain's industrial revolution, whilst holding China's development back. Along the way he dives in a mysterious lake in Oregon, climbs a glacier of salt, crawls through an extraordinary cave in Iran and takes a therapeutic bath in crude oil.

Professor Iain Stewart continues his epic exploration of how the planet has shaped human history. Iain sets sail on one of the fastest racing boats ever built to explore the story of our turbulent relationship with the wind. Travelling to iconic locations including the Sahara desert, the coast of West Africa and the South Pacific, Iain discovers how people have exploited the power of the wind for thousands of years. The wind is a force which at first sight appears chaotic. But the patterns that lie within the atmosphere have shaped the destiny of continents, and lie at the heart of some of the greatest turning points in human history.

Professor Iain Stewart continues his epic exploration of how the planet has shaped human history. Visiting spectacular locations in Iceland, the Middle East and India, Iain shows how control over water has been central to human existence. He takes a precarious flight in a motorised paraglider to experience the cycle of freshwater that we depend on, discovers how villagers in the foothills of the Himalayas have built a living bridge to cope with the monsoon, and visits Egypt to reveal the secret of the pharaohs' success. Throughout history, success has depended on our ability to adapt to and control constantly shifting sources of water.

Iain visits an extraordinary crystal cave in Mexico, drops down a hole in the Iranian desert and crawls through seven-thousand-year-old tunnels in Israel. His exploration reveals that throughout history, our ancestors were strangely drawn to fault lines, areas which connect the surface with the deep interior of the planet. These fault lines gave access to important resources, but also brought with them great danger.