Performance / A CERTAIN LEVEL OF DENIAL ICA, London

Six years ago, a 16-year-old black woman was found tied up in a bin-liner smeared in excrement. The press said she did it to herself and condemned her as a pervert. A year later, in outraged response, the veteran performance artist Karen Finley smeared her naked body with chocolate and performed a raw and furious show, We Keep Our Victims Ready, about the sexual, social, mental and physical abuse of women. It was too much for the US Government, who took away her National Endowment for the Arts (NEA) grant on grounds of obscenity. Now, five years later, her funding has been restored and she appeared in London for the first time this week with A Certain Level of Denial, inspired more by grief than by rage, but none the less angry for that.

The new show is inspired by the death of so many people from Aids, and in particular by the suicide of her friend and fellow artist Ethyl Eichelberger, who knew he was dying and so took his own life. Naked except for a feathery mother-of-the-bride-type hat, Finley demurely comes on to the stage, picks up her microphone and opens her mouth. Out of all proportion to the comfortableness of her body, Finley's voice is awe-inspiring, incantatory and shocking. She speaks as if in tongues, the poetry pouring out in all its lyrical, brutal, gut-wrenching guises, borrowing the rhythms of Southern preachers and black leaders. Sometimes the pitch rises to the screech of a furious inner child, screaming at the injustice of a world in which, if George Bush is taken ill, dozens rush to his aid, but "Nobody picks up my friend, nobody picks up my friend."

That voice gives rent to the suffering of a generation. Finley offers herself as a conduit for all the dysfunction, aggression and pain that our culture throws up and cannot deal with. Behind her, huge slides of her paintings tell the same story in a different medium. Sometimes she stands in front of the projections so that a word, "pain", is written across her body; or a bleeding heart flowers on her sex. Periodically, she applies articles of clothing to her body as symbols - a pair of camouflage trousers, white nylons and long gloves, a cotton nightdress.

There are many exorcisms going on in A Certain Level of Denial. As the onslaught of words overwhelms and the attention wanders, you find yourself coming up into a tirade about illegal abortion or about homophobia among affluent liberals or again about Aunt Enid's painstaking quilt of sorrow. As she performs, Finley appears to slip off into an inner world and the sneaking realisation dawns that, rather than performing for us, she is drawing on our collective energy to send herself into a shamanic state of ecstasy.

Unlike Memento Mori, Finley's installation in Newcastle, Los Angeles and New York, A Certain Level of Denial is not an interactive piece. There, audience members were invited to participate in a series of new grieving rituals: the tying of ribbons for the dead, the writing of lost names in sand, sitting with an empty "flower chair" to remember and commune with the departed. The effect, by all accounts, was richly emotional. As A Certain Level of Denial progresses, you begin to feel distant and drained as Finley goes through a catharsis that you are expected to sit quietly and watch. At a certain moment she started suddenly, gasped, and muttered "I can feel him." Perhaps the spirit of Ethyl Eichelberger had come to her call. If so, it was a strictly private experience, for Finley alone.