Beginning in the 1960s, a handful of young scientists headed out into the wilderness, driven to understand how nature works. Immersed in some of the most remote and spectacular places on Earth—from the majestic Serengeti to the Amazon jungle, and from the Arctic Ocean to Pacific tide pools—they discovered a single set of rules that govern life: The Serengeti Rules. Now in the twilight of their eminent careers, these five unsung heroes of modern ecology share their adventures, reveal how their pioneering work flips our view of nature on its head, and give us a chance to reimagine the world as it could and should be.