Neil Oliver follows in the footsteps of four Scottish explorers who planted ideas rather than flags - ideas that shaped the modern world we know today.

Set in the spectacular Yosemite Valley in California, this is the story of the father of the modern conservation movement and one of the founders of America's National Park movement. John Muir was a 19th-century adventurer who explored the natural world and devoted his life and work to persuade others to see the sacred beauty of his discoveries.