"Redbelt" is the 10th feature written and directed by David Mamet, and it's a pungent little number. Reports of its topicality have been exaggerated. Mixed martial arts may well be the rage these days, but this is pure 1947, a story that exists in its own shadowy universe of chicanery and ringside crises of the soul.

The film stars the marvelous Chiwitel Ejiofor - pronounced "Chew-eh-tell Edge-o-for" - as Mike Terry, a jujitsu master who runs a martial arts studio on the west side of Los Angeles, with his Brazilian-born bookkeeper wife, Sondra, played by Alice Braga. Like everything Mamet touches, whether predominantly comic or dramatic, this stern cautionary tale concerns whom we can trust (ourselves, if we live by a few simple, honorable rules of conduct) and whom we cannot (others, especially if they're in the film industry).

According to the great laws of film noir as established by "The Set-Up" and "Body and Soul," a man must face his demons in the only court a fighter answers to: the ring. Mike has chosen to avoid prizefighting all his life. He's in it for the purity and the Samurai-like code inherent in what he teaches.

Mike's specialty is Brazilian jujitsu, and his clientele leans toward off-duty cops, bouncers, all sorts. A minor car accident one night outside the studio leads to a mishap involving a loaded weapon inside the studio. The gun, belonging to an off-duty cop, is fired by a frazzled lawyer played by Emily Mortimer. (The staging of this key sequence feels contrived.) The bullet hits the front window. Mike hasn't the money to replace it. Sondra goes to her shark-like brother for a loan. The brother owns a bar, and one night when Mike's there, a Hollywood superstar, Chet Frank (Tim Allen, just right in his steely sense of movie-star privilege) shows up without an entourage. Mike comes to his aid when Chet's threatened by a drunk. With suspicious ease, Chet offers Mike a chance to co-produce his Desert Storm picture, which could use a better fight choreographer. Hollywood appears to be the answer to Mike's problems.

While Mamet's skills behind the camera have grown markedly since "House of Games" 21 years ago, there comes a moment in every Mamet film when you realize he'll never make the urgent, kinetic visual choice. It would be folly to expect him to direct like someone else. His philosophical stoicism as a director matches his stoicism on the page. (It's stoicism spiced with the toughest sarcastic taunts this side of Clifford Odets.) But in Mamet's "Heist," for example, the action slowed to a crawl in the climactic scene involving men running around an airport tarmac with guns.

The densely plotted "Redbelt" snakes along very well until the main event. Suddenly you're made aware of a lot of extras standing around unconvincingly while the protagonist reckons with his soul and his adversaries, and it's too bad, because the rest of the picture is very good.

Not everyone can act his material with ease. But Ejiofor, who brings a serene gravity to every exchange, was born to do Mamet. "Booze, women," Allen's Chet says, slyly. "What in this life doesn't get you in trouble?" Ejiofor's Mike responds simply: "Everything has a force. Embrace it or deflect it. Why oppose it?"