It's 1837 and a young man finds himself stranded high in the Rocky Mountains and thousands of miles of wilderness from home. After burying his father, a preacher bound for Oregon to bring religion to the "heathen Indians," Isaac Burns picks up his father's Hawken rifle and sets off on a journey that cannot end in anything but tragedy. And then, out of the darkness, strides a shaggy angel clad in buckskins and furs. His name is Noah Smythe, a mountain man who is struggling with his own personal battle to hold on to a world that will soon slip from his grasp. Reluctantly, he takes Isaac under his wing and they set off a incredible journey that will test both spirit and flesh and will reach its shattering climax in a wilderness rendezvous that will go down in legend as The Last Green River.