Kammer/Kammer, Sadler's Wells, London

Do you need to see Kammer/ Kammer, or is it enough to talk about it? William Forsythe's dance/theatre piece is so self-conscious, so busy regarding itself, that it hardly seems to happen at all.

Kammer/Kammer, brought to London as part of Dance Umbrella, is Forsythe's last work with Ballett Frankfurt, which he has led since 1984. It is characteristic of the experiments he made in Frankfurt, using speech and random philosophising. There are 20 dancers in Kammer/Kammer, but it's more play than ballet.

It shows two love stories, both gay and both unhappy. A professor fantasises about her student; a rock star's young boyfriend loses touch with his lover as they travel the world together. Attention to love is surprising from Forsythe, whose dourly athletic ballets never seem to have much time for shades of mood or feeling. And in fact it's hard to take love seriously in Kammer/Kammer: there's so much deconstruction, so little to deconstruct.

The ironies are built into a very tricksy staging, but they're part of Forsythe's source material. The professor story is from an essay by Anne Carson, who imagines herself as Catherine Deneuve playing a professor and keeps picking her own fantasy apart. Are you confused yet? Forsythe does mean you to be; the rock star's boyfriend, whose story is from Douglas A Martin's autobiography, complains as soon as he hears about it.

The love affairs are acted out on stage, but they're also filmed, projected live on to screens around the auditorium. Half the encounters take place behind bits of scenery, in hotel rooms turned away from the audience, so the screens show much more than the stage does.

Since this is about image and reality, Forsythe spends the evening pointing out the artifice of performance. We begin with a fake rehearsal, people warming up and arguing about scene changes. Antony Rizzi, playing the rock star's lover, keeps breaking off to talk to the audience, to his colleagues, to complain when they call him Tony. When he laments his breaking fictional relationship, he slides into whining self-pity: the onstage dancers make sarcastic "ahh" noises.

This is the trouble with Kammer/Kammer. Forsythe is showing characters whose fantasies dominate their lives, and who then collapse under them. Yet he never shows us the needs that drive all this.

They are all mannered performances. Dana Caspersen, who dances the Deneuve charac- ter, marks every philosophical point by twitching her eyebrows, every emotion by talking faster. As Deneuve and the boy become desperate, we're supposed to recognise real feeling breaking through the layers of irony. It's noisier certainly, but has no more depth.

There's very little dancing in all this. There are dancers, but their dances, like the rest of the action, are only really clear on screen. They fall on and off the hotel-room mattresses, writhe, stand knock-kneed and pigeon toed. They serve merely as background, another layer of distraction. Kammer/Kammer is all distractions and no heart.