Throughout history, a handful of unusually driven individuals have been inspired to explore the limits of the known world, inspiring us and changing our perceptions of our planet through their courageous adventures. What is it that makes these men and women risk their lives in desperate, often fatal efforts to discover distant and inaccessible places? Robin Hanbury-Tenison, himself one of the most distinguished explorers of the 20th century, looks at the greatest of their kind in history, bringing their experiences to life in vivid and compelling anecdotes and drawing on their own first-hand accounts. Among the explorers he features are some who are well known, like James Cook and David Livingstone, and some less so, such as Herodotus, the first European to record an expedition and Nain Singh, who walked huge distances to map the forbidden lands of Tibet, counting every pace. And he asks: what was it, and is it, that motivates these unusual people? And how have they enriched our world through their adventures?