Iain Stewart follows in the footsteps of the founding father of geology, James Hutton. This Scottish rogue was a profound and original thinker who, 250 years ago, overturned ancient beliefs about how and when the world was formed. His ideas clashed with those of the most eminent scientist of his day. Lord Kelvin was determined to prove Hutton wrong.

Iain Stewart finds out how gung-ho geologist Edward Bailey discovered Scotland was once home to super volcanoes. And how unsung hero Arthur Holmes solved the mystery of what makes continents move across the surface of the globe.

In the final episode, Iain Stewart finds out about daredevil scientist Louis Agassiz, who first imagined the world had been gripped by an ice age. Plus, the story of humble janitor James Croll, who used the planets to work out the natural rhythms of the earth's climate.