There are some words that I try never to use when describing any movie - try, I say, and often I do not succeed - "poetic," "mystic," "hazy," "dreamy," words like that. I want to use every single one of them in discussing The Assassination of Jesse James by the Coward Robert Ford.

For you see, The Assassination of Jesse James by the Coward Robert Ford (a title that I adore beyond all measure and have no interest in abbreviating) is a film whose many characteristics as narrative, as character study, as post-modern breakdown of the Western genre, are all subservient in my eternal film undergrad's eyes to the absolutely flawless cinematography. Cinematography that looks like the stuff of myth, the stuff of dreams and hallucinations. Cinematography that is perhaps the most beautiful work I have ever seen from one of the greatest living masters of the art, Roger Deakins, the mind behind such visual masterpieces as Fargo and O Brother, Where Art Thou? and at least a couple things that weren't directed by the Coens.

The Assassination of Jesse James by the Coward Robert Ford begins in September, 1881, seven months before Robert Ford (Casey Affleck), a coward, assassinated Jesse James (Brad Pitt), right about the time that the West was clearly beginning to pass away (Colorado had been made a state in 1876; the Dakotas and Montana would join in 1889 and Wyoming in 1890). It is therefore yet another example of one of the commonest - even clichΓ©d - subgenres of the Western, the Death of the Frontier film, in which an event or individual is metaphorically used an example of all the things that had to fade into history if civilisation was to move onward.

What sets The Assassination &c apart from the basic model of this type is its entirely self-conscious desire to be seen as mythology, or at least legend. There are mythic elements in neo-Westerns from the nameless archetypes of The Good, the Bad and the Ugly to the ethereal winter of McCabe & Mrs. Miller to the storybook man of notoriously vicious and intemperate disposition at the heart of Unforgiven, but none of those films have what this film has: a narrator.

Now, I usually hate narration like no other, and almost everything I hate about it is on full display here: it makes obvious what should be implicit, it tells us things that were better shown, it interprets the actors' performances. But there must always be exceptions to all things, and here is an example of narration that not only pleases me, it is a fundamental part of what I understand the film to be. The impersonal, slightly bookish-sounding voice (provided by Hugh Ross) puts a wall up between the audience and the film, dispassionately rendering everything in some undefined past tense. But it's not the voice of a History Channel narrator, because of the content of the narration. The narrator's syntax is, not exactly florid, but certainly a bit twisty and archaic. It is by turns vague and specific, occasionally describing for us precisely what we're watching (another thing that I ought to hate about it), and the effect is ultimately that of a storyteller. Thus, a level of narrativity is layered on top of the film: we aren't watching the final days of Jesse James, we are watching a story of the final days of Jesse James.

Thus do I return to the cinematography. In most of the instances that there is narration, there is also a diffracting filter on the lens that blurs the edges of the frames and puts prismatic colors around the edges of all the shapes. It is like watching the film through a glass, darkly; or perhaps through the eye of an old still camera. I won't say that it makes the film seem old, because that isn't at all right, but it makes the film seem distant, hard to capture.

There's a very good word to describe the look of the film that I didn't hope to use, but: painterly. Which means that everything feels more like a palette than an actual physical space, and that makes it seem more like a series of illuminations than a "movie." It is beautiful in the abstract, and it helps to increase the sense of myth. I'll shut up about the cinematography now.

The myth being told is about a young man who has a hero: a man he wishes to be, a man he is in love with, a man he is jealous of, and for all these reasons, he chooses to kill the man. Casey Affleck, in a performance that should make him a star if there's even a trace of justice to the world, brings all of these neurotic emotions to the fore without feeling "actorly." He also speaks in a cracking, pubescent voice that underlines Ford's immaturity, that would lead him to emulate and idolise a vicious thug like Jesse James. That's the other part of the myth: Jesse James is a dark man in this film. Not a bad criminal, like he was in Sam Fuller's I Shot Jesse James (a film that could not be further from this treatment on the same material, in almost every possible way); a threatening force, rarely explicitly evil but always on the edge of exploding into violence. It's a role unlike anything else in Brad Pitt's career, and it's the best work of his career partly for that reason, and partly because Pitt commits fully to being an unsympathetic bastard who could kill you like that.

They're the two standout performances because they're the two biggest roles, but this is a film startlingly full of impeccable small characters. A partial list of the actors in the film includes Mary-Louise Parker, Sam Shepard, Sam Rockwell (totally unrecognisable as Charlie Ford), Michael Parks, Zooey Deschanel, Ted Levine, and most pleasingly to this Deadwood fan, Garrett Dillahunt, looking so eerily like Casey Affleck that it makes one weep that the scheduling didn't work out to have him play Bob Ford's brother, as was originally planned. All are just famous enough to be familiar, but none are superstars who rise above the character, and all of them are really good. There hasn't been a film all year with such a perfectly lived-in ensemble.

Andrew Dominik, directing only his second feature (I have not seen Chopper, his 2000 debut), has made an astounding work of mythological storytelling, not exploding the West so much as burrowing in and revising it, and making it his own. This is a truly great Western, and a truly beautiful film.