After America purchases the vast territory of Louisiana from France, Thomas Jefferson needs for this new land to be explored and mapped. From 1804-1806, Meriwether Lewis and William Clark lead an expedition across what we now call the American West. With the help of a Shoshone guide named Sacagawea, the group manages to reach the Pacific Ocean. Along the way, they map the land, discover new animals, and make contact with Native American tribes.