OPERA / All Reich on the night: Kind of. Robert Maycock on The Cave, composer Steve Reich's collaboration with video artist Beryl Korot

It's like a game of Chinese whispers lasting thousands of years. You ask the question 'Who was Abraham?' or 'Who was Isaac?' and you collect answers as they pass along a chain that stretches around the Middle East and across the Atlantic. The answers gradually lose focus but gain in flair. Confidence is replaced by uncertainty, but the sharp antagonisms that come from contrary hearings are softened. The current state is diverse, sometimes frivolous, showing a love of invention and a gift for bullshit: Ishmael as 'the James Dean of the Old Testament', Hagar as the maid who 'started elevating herself'.

If that sounds like a potted parable of cultural history, you're on the same wavelength as Steve Reich and Beryl Korot. The Cave takes its name from Abraham's burial place, supposedly the way into the Garden of Eden. The location, Hebron on the West Bank, is known, but the site is inaccessible because it has long been built over. You have to use your imagination.

The sheer joy of creation for its own sake has usually been at the heart of Reich's music. When he started building long pieces out of repeating, overlapping, shifting phrases, the performers' tasks were mechanical and uncreative but highly skilled. He made sure to tour with his own group of musicians so that there always appeared to be a pride in craftsmanship that reflected the precision and ingenuity of the composing.

Nowadays the music is freer and quicker-changing, while the attitude remains. It would make him an impossible collaborator with a librettist, unless the writer had unlikely talents for timing and self-effacement. But collaboration is built into the fabric of his work, and some kind of multi-media potential was always there. The method he has found is characteristic: record the words, record the images, and compose with them too.

What emerges isn't radically new, but it's slick. Korot's video material consists mostly of interviews, which flash up in patterns that stem from the same rhythmic impulses as the score, while the music itself grows out of the way the subjects talk. First sight is not promising: a triple-decker metal gantry with performing areas on each level - Mark II of the Death of Klinghoffer set, or Mark Umpteen of Einstein on the Beach.

There's occasional movement up and down a pair of spiral staircases, or on and off stage, as the 13 players and four singers change line-ups. Action focuses on the gantry's five screens, as faces spring into life, voices echo themselves, printed words in several languages chase each other in canon, cameras scan in endless cycles around what remains of the Hebron sites. The effect is like an austere and polished synthesis of pop videos and conference presentations. Fair enough: Reich has always related in sophisticated ways to musical vernaculars, sometimes to verbal ones; now, visual.

What you hear is also a synthesis. The Cave takes in the simple pulsations of Clapping Music and the nimble light-voiced singing of Tehillim, the imitation of spoken phrases in Different Trains and the punchy syncopations in the Sextet. Reich starts cleverly with computer operators hammering their controls, each stroke bringing up a word on screen - a sort of audiovisual rap. The creative delight bursts out of the phrases he finds to follow what interviewees are saying. People don't talk the tunes any more than Messiaen's birds sing them, but they inspire delicious melodic turns, some so direct and apt that they would make the stoniest audience smile. One speech from an American needs only a touch of underlining by a cello to turn into a catchy aria. On the way home the lilt of the late-night announcer at Waterloo East sounded like an offcut.

It's here that the troubles of The Cave start. In itself the music's emotional colouring is limited, as usual, to the infectious pleasure of discovery. The only way it can convey a wider range is through the verbal overlays - the feeling evaporates as soon as the spoken phrase translates into pure music. Here and there you are moved, but by a thought or a gesture or a facial expression. The most directly affecting music is a couple of minutes of recorded Muslim recitation.

All this means you are swayed by the choice and ordering of the material. If I were a Palestinian Muslim I would be feeling short-changed. Israel has the first and longest act, America the last, and they share an up-tempo, high-tech ambience; the 'Arab' act, squeezed in between, seems relatively undeveloped. Reich treats his more whimsical and rootless fellow natives with some irony, but the final image, intended or not, is of the US as culmination, putting the scars of cultural difference at a distance.

Three acts stretching over two hours bring problems of continuity. Reich writes in short sections, constantly changing pace. He holds the attention by switching instrumental and vocal colour, but only the final stages generate real momentum; the rest holds together more through shared method than material. Is this the much-touted future of opera? Hardly: the principals don't sing, and there's no theatre to speak of. But it's certainly the work of a composer with the vitality to keep on exploring.

(Photograph omitted)