This film provides the saga of a legendary Wild Bill Hickock. He, Buffalo Bill Cody, and Calamity Jane, are the central characters.
As the Civil War closes, Lincoln mentions his concern that the country's dynamism would be enhanced if people would follow the advice, "Go West, young man," which, mercifully, the film didn't erroneously attribute to Horace Greeley, as a number of others did. But then, he gets assassinated, and some financiers speculate that they can get rich selling weapons to the American Indians.
In the meantime, we see Wild Bill Hickock, who interacts with a small boy, while a steamboat is loading at a dock along the Mississippi. Wild Bill uses a Bowie knife, which he eventually gives to the boy, calling it an "Arkansas Toothpick," which in reality was a different type of knife, though both were used throughout the frontier.
Hickock eventually meets Buffalo Bill Cody, who looks close to the photographs and paintings of the actual man. Cody has just gotten married, and is bringing his bride to the Old West to settle down.
When they arrive at their destination, they run into Calamity Jane, who has a crush on Hickock. She looks at Cody's wife, and asks Buffalo Bill, "Is this your mopsy?" The line was one that caused the Hayes Board some problem, since one definition of "mopsy" was prostitute. Demille wanted the line in, and one of his aides pointed out that in Beatrix Potter's books about Peter Rabbit, three of the rabbits were Flopsy, Mopsy, and Cottontail. He pointed this out and asked the censors to identify "the rabbit of ill virtue." It worked; the line stayed in.
The Indians were getting restless, in part because of the superior weaponry they got from the agent of the Eastern financiers. Cody and Hickock were asked to help scout the area, so that troops could get safely through to a beleaguered area. Cody led the troops; Hickock went to check out the activities of an Indian chief, who was an old acquaintance, and who was leading some of the hostile Indians.
Calamity Jane gets captured, and Hickock gets captured trying to save her. They are brought to the chief, and although neither would talk, torture applied to Hickock breaks Calamity Jane's willpower, and she tells the route Cody is using.
The two are released, and Hickock joins up with Cody and his forces, in part to alert them they're walking into a trap. With Hickok's help, they hold off the Indian attack.
Hickock decides to go after the gun runners, and finally takes them prisoner. As they're waiting for authorities, Hickock is gunned down by being shot in the back while playing cards.
There are numerous historic anomalies in the film, but it retains the flavor of legend. Pretty good for the 1930s.

The Godfather Part I was a stunning look inside the fictional Corleone family and how an innocent young man was all but forced into circumstances he never wanted to have a part of. The Godfather Part II shows that young man's acceptance of his new role, his desensitization of character, as well as his complete loss of all innocence as he dives deeper and deeper into a life of crime. The first two parts of this saga of this transformation of Michael Corleone make for one of the greatest tragedies in cinematic history.
Then, along came The Godfather Part III. Michael Corleone is now the aging Don of the Corleone family. He shows remorse for his previous actions not through subtle behaviors, but by trying to use his powers for good and admitting all his wrongdoings and regrets to others. Very cliche and uncharacteristic of the complex character that is Michael Corleone. Michael's plans to use his powers for good are derailed by an ambitious young disciple and his enemies. Michael's daughter is eventually a casualty of the ongoing mob wars and her death predictably leads to Michael realizing that his entire life as Don has been worthless for he has failed in the one thing that was the reason for putting himself into the position he was in: protecting his family.
The Godfather Part II ends with Michael Corleone reaching the lowest of the lows: having his own brother killed. Before Part III was made, the Godfather saga was an emotionally riveting tale of an innocent young man's journey into darkness with the unbelievably tragic end of Michael forgetting his roots and abandoning the one thing that has always mattered most to him and those around him: family loyalty. Part III paints the picture of Michael as a man who is and always has been just a victim of circumstance. This greatly corrupts the meaning of the first two films.
The Godfather Part III is a horrible mess of a film that never should have been made. The only solution to the problem that is this final installment of The Godfather movies is to pretend that it does not exist and that the saga actually ends with Michael's shockingly horrible act of having a member of his own family killed.