 The two men join an expedition organised by Zeb and Frenchy, who owns a sailing barge called 'Mandan'.Taking about 30 other trappers with them, they begin to travel 2,000 miles up the Missouri and into the Yellowstone River to seek trade with the Blackfoot Indians, in competition with the Missouri Fur Company.Zeb has brought along Teal Eye (Elizabeth Threatt), a pretty Blackfoot woman Zeb had found several years earlier after she had escaped from an enemy tribe.