A cornball martial arts movie in Mametspeak? It sounds like a joke, but unfortunately “Redbelt” is presented with the utmost seriousness, which makes it all the more ridiculous. This is like a Chuck Norris picture played with the solemnity of a Shakespearean tragedy. It’s almost as gloomy as Rod Serling’s “Requiem for a Heavyweight.”

This being Mamet, of course, the script has its quota of sleight-of-hand and misdirection. But that element is really a minor aspect of a plot that follows the traditional formula of the honorable fighter who’s manipulated into entering a for-money tournament against his will. The central figure is Mike Terry (Chiwetel Ejiofor), a Los Angeles jiu-jitsu teacher who refuses to enter competitions because, he opines, they demean the purity of the discipline, even though his wife (Alice Braga), an ambitious woman who manages his struggling academy as a sideline to her own clothing business, points out that he’s going broke.

Two events change his routine. One involves a troubled lawyer (Emily Mortimer), hopped up on prescription drugs, who not only damages his parked car on a rainy night but, when she comes in to admit the accident, grabs the pistol of one of Mike’s prize students, a policeman (Max Martini), firing it and shattering the school’s front window. The cop is willing to cover up the business to save her a potentially career-destroying scandal, and Terry tries to help her by teaching her some defensive moves, but the ripples from the incident will have serious consequences.

Mike’s dire financial prospects are also affected by a chance encounter with movie star Chet Frank (Tim Allen), whom he saves from a beating in a neighborhood bar, and who promises to be a generous benefactor to both Terry and his wife.

Unfortunately, what results for the instructor is involvement with a bunch of dangerous types, including a slick agent (Joe Mantegna), a loan shark (David Paymer), a fight promoter (Ricky Jay) and his unscrupulous brother-in-law (Rodrigo Santoro), the bar’s owner who also dabbles in the fight game. And it all leads to Mike’s reluctant participation in a big martial-arts tournament that—like Claude Rains’s Captain Renault in “Casablanca”–he’s shocked, shocked to discover is rigged! And he yet manages to emerge from it not only with his honor intact, but his status enhanced—though through a series of events that not only strains but shatters credulity.

One can understand why Mamet wrote “Redbelt.” He’s a student of jiu-jitsu himself, and obviously considers it an honorable pastime that can be corrupted by lowlives out to turn it into a wrestling-style entertainment. But his enthusiasm has led him into the mistaken belief that he can somehow transform the clunky cliches of the genre into dramatic gold by a sheer act of will. His script has a few moments when his knack for idiosyncratic dialogue carries the day, but overall it comes across as a silly piece of work that might have worked as parody but is ludicrous when presented as a misguided paean to integrity.

There isn’t much compensation to be had in the look of the picture, which is pretty dank and muddy, especially in the fight scenes, which as choreographed, shot by Robert Elswit and edited by Barbara Tulliver, are pretty much a mess. But some of the actors add some zest, especially Mamet veteran Mantegna and the reliable Paymer, as well as Mortimer and Allen, with the former stymied only in a hilariously uplifting finale and the latter playing nicely against type as the gruff movie star. On the other hand, the usually impressive Ejiofor is hobbled by writing that turns him into a plastic saint and dialogue that often sounds as if it came out of a fortune cookie, and Jay—another Mamet regular—is curiously ill-at-ease in delivering his lines. Braga, Santoro and Martini just get by.

In jiu-jitsu jargon, the redbelt supposedly represents the highest achievement. It’s a recognition Mamet’s movie certainly does not deserve.