Red Belt, 15

Quite a week for unfettered machismo, and few directors have indulged themselves so consistently on the theme as David Mamet.

You hear it in the way his men – and nearly all his major characters are men – cajole and intimidate one another, even when they're supposed to be friends. Redbelt, his latest, is a curious one, a movie that hints at greatness only to retreat, unpardonably, into genre convention. Chiwetel Ejiofor plays Mike Terry, a ju-jitsu instructor who runs a lowly training school in Los Angeles. One night, a distraught lawyer (Emily Mortimer) stumbles in and, during an altercation with an off-duty cop, discharges a handgun: no one's hurt, but the accident will reverberate when Mike, desperate for money, helps out a washed-up Hollywood action star (Tim Allen) and finds that no good deed goes unpunished.

A principled guy who conducts all business as a matter of honour, Mike is drawn in to a world of favours and gifts, but no sooner is he welcomed into it than he's suddenly, and chillingly, excluded. The Mamet dialogue is in overdrive: "Let the wheel come around, let the wheel come around", "The first step – to leave the outside outside", "There is no situation you cannot escape from". It's entertaining in its way, so long as you accept that it sounds nothing like what you'd hear from an actual human being. As Mike's problems begin to mount, Redbelt puts a grip on us – and then lets go. Somehow the taut moral drama slackens and we're plunged instead into a sort of high-toned wrestling movie, with Mike doing an On the Waterfront stagger-of-integrity à la Brando so as to reclaim his good name. Ejiofor, by the way, is magnificent, almost as good as he was in his breakout role in Dirty Pretty Things some years ago. Heartening to know it wasn't a fluke, but he still can't turn this movie around. Did I say On the Waterfront? Actually, more like The Karate Kid.