According to the publicity, this collaboration between an American black men's performance collective, the Hittite Empire, and a British company, Chakra Zulu, tells of "12 men blasted through time, reborn in the sweltering, sulphur-filled air of the prison-asteroid Planet Alabama. Looking back light years, the prisoners pick at the bleached ones of the African diaspora."

So now I know, because I was none the wiser after watching what was happening on stage. This commission from the London International Festival of Theatre is one of the most inept pieces ever to have been staged under the auspices of a major festival.

When it is not unintelligible it is offensive. Why is it that if a group of white men stood up on stage and blamed black people for all the ills of the world, it would rightly be called racist - but when a group of black men stand on stage and castigate white people it is deemed to be art?

White people are represented here by a white man who refers to the inmates of Planet Alabama as "niglets" and declares: "I am Jeffrey Dahmer and you are food to me. I'm God. My whiteness makes me God. I want to fuck you in the arse."

There is so much more in this vein that, although the script is credited to two people, you begin to wonder if the cast is making it up on the hoof.

The evening's only real moment of truth comes when the performers leave the stage, come into the audience and tell us to whom they are individually dedicating the performance. Behind each of these dedications are stories that should be told and must be heard.

At one point, one of the cast members declares: "We've got light, sound and fucking technicians but that don't make it theatre, that makes it enchanted ritual." Sorry, mate, you may be able to kid yourselves, but you can't kid an audience.

At Riverside Studios, London, until July 7. Box office: 020-7863 8017.

London International Festival of Theatre