1850's America. The eponymous JJ flees the battlefront in Mexico and becomes a self-sufficient mountain-man. With his life on track (native wife, natural resources ludicrously abundant), he inadvertently offends an Indian tribe and is subject to a vicious, never-ending vendetta. It always happens to the quiet ones...
A superior mountain-man movie with Redford as a naive 1850s ex-soldier who, deciding he wants to go back to nature, has a tough time at first, but then after some eccentric teaching from a bear-hunting hermit (Geer), learns the secrets of life in the wilderness.
This is obviously about a character being transformed into a myth and also explicitly about the ecology of the wilderness, with lots of reverence for plant and animal life, Indian rituals and the changing seasons. Redford just about convinces as the outdoor hero in animal skins, but what finally redeems the film are its rugged Utah locations, sense of place and convincing faith in the powers of nature.
Pollack does right to put his faith in one man and a whole lot of mountains. The result is impressive.