When Steve Sillett was 19 years old, he free-climbed – with no safety equipment and no training – one of the tallest trees on earth, in the redwood forests of Prairie Creek, California. 30 storeys above the ground he glimpsed an undiscovered ecosystem, and his passion for that astonishing world would transform the rest of his life. Over the next twenty years, Sillett and a close group of friends charted this system, discovering mosses and lichen never seen before, and travelling among branches so densely interwoven they form incredible sky-high walkways. There are only twenty people on earth who have climbed the world’s tallest trees and who know their location. In writing The Wild Trees, Richard Preston not only managed to gain access to this group, but began to climb these hidden giants himself, putting his life in danger in order to understand the powerful connection between the massive trees and the world’s last great explorers.