America is home to the world's tallest tree, its biggest tree, and some of its oldest — silent forces that have guided human evolution and history since the spark of civilization. There's just one problem: we don't know how to stop killing them. In his family camper van, nicknamed the Mystery Machine, Greg Melville sets out to find these last ancient survivors while he still can, among them a nearly 5,000-year-old bristlecone pine, a giant sequoia as wide as a house, and an unassuming Manhattan elm older than the city around it. Filled with misadventure, this wry, insightful, and surprisingly moving book is a walk in the woods like no other.