One of the challenges of being a great artist is that not all of your art is going to be great. The Beatles wrote several songs that lesser acts would have turned into careers, but that nonetheless lack the power of "Yesterday" or the joy of "I Wanna Hold Your Hand"; George Orwell's The Road to Wigan Pier is an excellent work of journalism, but not nearly as good as Homage to Catalonia. Redbelt, the latest film from writer-director David Mamet, is not as impressive or thought-provoking as some of his other dramatic works, like Glengarry Glen Ross or House of Games or Oleanna; at the same time, it's an exciting, engaging mix of drama and action supported by an immensely appealing lead performance by Chiwetel Ejiofor (Dirty Pretty Things, Children of Men).

Redbelt's subject and setting may make it seem incongruous -- Why is one of America's greatest playwrights making a film about mixed martial arts and Jiu-jitsu? -- but it's actually in keeping with Mamet's other recent entertainments like Spartan, his work as a co-creator of The Unit and his pseudonymous work on the screenplay for Ronin. Redbelt fits in with these projects: They have a kind of heroic stoicism under them; they're stories of honorable men in a dishonorable world. They've all got a kind of muscular poetry, too, a hard-bitten nobility that's still a little sad about the edges.

Mike Terry (Ejiofor) owns a Jiu-jitsu studio in downtown L.A.; he has the respect of his students and plenty of bills to pay. Mike's training and philosophies are unorthodox; he believes "competition weakens the fighter," and also uses a handicapping method for practice bouts where contestants draw marbles; two marbles are black, but if you draw the one white one, you get a handicap -- your arm bound to your side, for one example. But life doesn't wait for you to draw marbles to throw you a curveball.

One night, distraught attorney Laura (Emily Mortimer) drives by the studio and has an accident; she comes in to do the right thing, but something very wrong happens instead, and damage is done. And yet, Mike and his student Joe (Max Martini) set things right as best they can and refuse to press the matter. Mike's wife Sondra (Alice Braga) sends Mike to her club owner brother Bruno (Rodrigo Santoro for a loan to fix what Laura's ruined; at the club, Mike learns a few things he doesn't like and saves boozy, woozy action star Chet Frank (Tim Allen) from a beating by dispatching several thugs with skill and will.

Mike's nightclub fight draws some attention (a cop notes "Lenny and Loomis saw the tape; they said it was better than Titanic."), and Chet reaches out to Mike, asking him for input on a film he's working on, asking him to serve as a producer. Chet's wife may even have some leads for Sondra's fabric business. It seems as if Mike's strict adherence to his code has put him in the right place at the right time. All it's done is put him in the right place at the right time to learn that others do not have his code. Small kindnesses have large ramifications, bad things happen to good people and Mike's forced to enter the world of pay-per-view mixed martial arts -- a rank commercialization of a thing he believes is beyond commerce.

This brief synopsis doesn't do Redbelt justice; it's full of revelations and reversals, moments when minor characters take on a major role and snap decisions have lingering effects. But the heart of the film is Ejiofor's performance as Mike. Chet tries to pin down what Mike does: "But you train people to fight." He corrects them, gently: "No, I train people to prevail." A lot of that training is spoken as aphorisms, Zen koans, homilies: "A man distracted is a man defeated." "There is no situation from which you cannot escape."

But as people of low character (but, it should be noted, high standing) set snares for Mike and break promises and try to make him play their game, he'll have to see if he can apply what he says he's been teaching. Redbelt, not coincidentally, echoes many of the themes of Mamet's recent book of essays Bambi vs. Godzilla: On the Nature, Purpose and Practice of the Movie Industry: Artists and craftsmen will perpetually be exploited by businessmen who lack those abilities but nonetheless think they know how to best sell art and craft to the maximum possible audience for maximum possible profit.

Ejiofor makes all Mike's physical and moral struggles fascinating. Mike's not a plaster saint or a four-color superhero; he's a man with strengths and weaknesses, a man whose ideas are going to be tested. Mortimer is good, as well, even if she's not as comfortable with the flat repetitions and blunt phrases of Mamet-speak as some of the other actors. Allen is surprisingly engaging -- he's playing a leading man who's also a bit of a punchline, but he pulls off the combination of self-hatred and screen presence the part requires. But we, and the movie, keep coming back to Ejiofor, and he earns that attention in every scene.

Redbelt looks like a conventional martial arts or classic boxing film as it leads up to the big fight, but it's actually concerned with something much more interesting -- the larger battle of if you should or should not have the big fight the world wants you have. The ambition and the sprawl of the film aren't matched by the cinematography; Redbelt may be set in the enormity and strangeness of L.A., but there are few exterior shots, and considering the film's subthemes of life in the modern world, we get almost no shots of the city that's shaping events in the film.

And while Redbelt is certainly passionate, and informed by the fact that Mamet's studied Jiu-jutsu for years (many luminaries in the fight world have supporting parts, as well), it still feels like a minor work. Still, even minor Mamet can be a source of major satisfaction, especially with an actor as compelling as Ejiofor in the lead. Redbelt looks like a fairly traditional film about how one man fights, but what makes it worth watching is that it's really a film about how one man prevails.