Akram Khan/Sidi Larbi Cherkaoui, Sadler's Wells, London

How good it is to be proved wrong. The overriding impression of Zero Degrees, the 70-minute work that opened the day after the London bombings, is of two deeply serious artists keen to address big issues on an intimate scale. As Khan and Cherkaoui walk to the front edge of the vast, bare Sadler's Wells stage, sit down cross-legged and begin to talk, it feels as if you've stumbled in on some private conversation.

The narrative thread of their duet follows a train journey Khan once made from Bangladesh to India. In the course of it he witnessed the death of a fellow passenger and was later hassled by border guards who wanted someone to blame. The story is told in stereo, by both dancers at once, unifying not only the gestures of their heads and hands - which creates a compelling little dance in itself - but the inflections and hesitations of casual speech, delivered as a musical score.

It's as if both men had that experience on the train - that their identities have merged. And the connection continues through the movement that follows, Cherkaoui adapting his wispy frame to the sturdy stamped rhythms of Khan's heritage, Khan bending his more grounded physique to the rubbery contortions of Cherkaoui. Yet what begins as a friendly, almost beatific exchange soon acquires a germ of something more sinister, of a growing power struggle with a winner and loser.

Gormley's contribution lies in a pair of articulated silicone figures made from live casts of each dancer, and their mute, uncomprehending stare adds another layer to the sense of witness and witnessed, bully and bullied, living and inert. Mostly the dummies are simply lugged about or propped up to stand and stare, but when Cherkaoui's double appears to give him a mighty slap in the face it comes as more shocking than funny.

Sawhney's music - generated live on stage behind a screen - is gloriously varied and affecting, ranging through swooning melismas on Indian sarod, to Asian dub and classical string trio. Yet the strength of Zero Degrees lies not in the accomplishment of its various parts, but in the ultimate sense of incompleteness.

When Khan finally reaches the last bit of his story, his voice trails off as if suddenly aware that there's no moral to be drawn, that he has no idea why he should be so affected by the death of someone he didn't know. Likewise, the choreography staggers to a close without conclusion. It's this humility in the face of unanswerable questions - specifically, about selfhood and death - that makes the piece so poignantly of-the-moment.

jenny.gilbert@independent.co.uk