Wilco / Shepherd's Bush Empire, London

Wilco's singer-songwriter Jeff Tweedy was maimed by rock 'n' roll, tamed by rock 'n' roll, named by rock 'n' roll, according to the most wistful song on his band's sprawling new double album, Being There. The record is a reverie on the sounds and excitements of the past, on what it means to play rock 'n' roll, and to listen to it. Wilco believe in rock 'n' roll in a touching, silly way - as a sacred essence. It's faith that gives them charm, but also sets their music's limits. On the last night of their British tour, faith and music were stretched to breaking- point. For a riveting half hour, it seemed to everyone who heard them, absurdly but undeniably, that rock 'n' roll itself was hanging in the balance.

For an hour before that, it was just a gig. Wilco strolled on, looking like Seventies hippies, and played like it, too. They exchanged scissor- kicks, and stretched their songs into "jams". "I want to fuck you up with rock 'n' roll," Tweedy sang, but it didn't seem likely. Until it dawned on Wilco that no one in the unmoving audience cared what they did. It was business as usual on a blase London Sunday. But to Tweedy, such behaviour at a gig was unacceptable - an insult to rock 'n' roll. He wasn't going to let it pass. He stopped the music, to spit his contempt at the crowd. He called them "snotty Brits". He offered to fight them.

Then he sang a song. On record, "Kingpin" is unremarkable. In the heat of Tweedy's fury, it became gigantic. He began delicately, as if he was playing to himself now. But every word had new meaning. Singing "hand- claps", he mimed the motion spastically to the crowd. Wilco drowned him in squalling noise, till all you could hear was three words - "I'm not kidding" - sung over and over, the singer still, staring, raging. Assaulted by indifference, the band were revelling in revenge. Finally, they walked off. And the crowd, in awe, stomped them back.

Wilco returned almost sheepishly, and Tweedy made peace. But the night's transformation wasn't finished, he knew more had to be done. So he hurled himself into the crowd, to touch as many people as he could, to make them move. He was a rock 'n' roll anti-body, a gig's desperate cure. He was forcing them to remember what a gig was for.

As the emotions Wilco had tapped died down, you could hear how ordinary much of the music was, why some of the indifference had occurred. But for precious minutes, everyone's sights had been raised. Sometimes, faith is enough.

Nick Hasted