DESC: America had not thoroughly explored the Louisiana Purchase obtained from Napoleon's France until Thomas Jefferson sent his secretary on an expedition through the territory. Merriweather Lewis enlisted his friend William Clark to lead the journey with him and in 1804 they set out to explore this massive tract of land. Eventually the pair was joined by Toussaint Charbonneau and his Indian wife, Sacagawea, who proved to be a valuable interpreter of the native languages. Lewis and Clark were presumed dead until their return to St. Louis in 1806. This National Geographic presentation examines this important adventure in American history. Narrated by Jeff Bridges, a veteran western actor.