Flare O'Flaherty, of Irish descent, mountain man and gambler, agrees to lead a group of missionaries down the Snake River to the remote headquarters of Hudson's Bay Company. Along the way, he faces the greatest challenges of a wandering man's lifetime in the form of Margaret Jewel, a beautiful, strong-willed teacher of Indian children, and a young Shoshone, Sima, seeking the white father he never knew. Together they would find their destiny along the mighty river that bore the shape of a serpent and held the promise of home.