Gritty, bloody saga of a man, left for dead by fellow trappers after being ripped to shreds by a bear, who drags himself through the winter wilderness to get his revenge on those who left him behind.
A true story, though if you want to look it up on the Internet, the mountain man's real name was Hugh Glass (not "Zachary Bass"). He managed (with no equipment or weapons) to get 200-300 miles to Fort Kiowa, and actually took no revenge on either of the two men who left him to die. One, interestingly enough, was a youth -- later very famous -- named Jim Bridger.
The movie leaves out a few details, such as his rolling in rotting logs so that maggots would clean out the infected wounds, since the real story defies belief, but Richard Harris does a superlative job in bringing this amazing character to life. Huston does his usual great job as the loony expedition leader, of course. I've seen this three times and still enjoy it. It leaves you with a rather unpleasant feeling that we modern men are a pretty sorry bunch of pussies by comparison