As the dramatic era of the fur trade draws to a close, a young man named William T. Hamilton seeks adventure on the high plains and mountains of the American West. Known to his friends as Bill, young Hamilton joins forces with distant relative Old Bill Williams, one of the frontier’s best-known mountain men and trappers. Under Old Bill’s tutelage, Hamilton receives a swift education in Plains Indian Sign Language and soon becomes an expert in the hand gestures that can mean the difference between life and death in the far west. During the early 1840s, Hamilton and Williams share a series of adventures while trading among the Cheyenne and Sioux. Then, they set off for the distant Blue Mountains, where the rivers and streams are said to be filled with beaver. However, the freewheeling lifestyle that Williams and Hamilton enjoy is challenged by a massive party of Bannock warriors. Armed with rifles, Colt pistols, and shotguns, the two men dig in for what could be their last stand.