Bradley Garrett is a social geographer, whose previous book was Explore Everything: Place-Hacking the City, an account of his time with urban explorers, trespassing into ruins, tunnels and high-rise buildings and construction sites. Bunker is a similarly entertaining account of the world of Doomsday preppers and their plans. It's an unsettling look at a growing movement, and an insight into our age of disquiet and dread. He goes to extraordinary places with great courage, and engages with some terrifying people, and he concludes that "the time to hunker down and out-think extinction is upon us. Again."