Follow the adventures and travels of four of the greatest explorers of all time in this three-part docudrama that recreates the epic journeys of some of the most intrepid explorers in history: Lewis & Clark, Alexander von Humboldt and Ernest Shackleton. Lewis & Clark were the first men to cross America in search of a trade route from east to west, and their expedition is legendary. Alexander von Humboldt was a German naturalist and geographer who traveled to South America in the late 18th century to map the flora, fauna and topography of this vast continent. Ernest Shackleton's voyage to cross Antarctica went badly wrong, and he spent the next two years trying to rescue himself and his men. Relive the heroic adventures of these remarkable pioneers in this breathtaking series from the BBC.