Sent by President Thomas Jefferson to find the fabled Northwest Passage, Meriweather Lewis and William Clark led the most important expedition in American history - a voyage of danger and discovery from St. Louis to the headwaters of the Missouri River, over the Continental Divide to the Pacific. It was the United States' first exploration of the West and one of the nation's most enduring adventures. This films tells the story of the entire Corps of Discovery- including the young army men, French-Canadian boatmen, Clark's African-American slave, and the Shonshone woman named Sacagawea, who brought along her infant son. A film by Ken Burns. Includes behind-the-scenes look; conversation with Ken Burns; and an interview with the producers and author. .