Iain Stewart tours the perilous and spectacular landscape of the Pacific Rim to discover how the rocks beneath our feet have shaped human history. In Peru, he reveals how the Incas were able to build a huge and successful empire in some of the most hostile and unforgiving terrain on the planet. He climbs high into the Andes to reveal clues hidden in the landscape, which show how the Incas mastered their rocky world and fed their millions.