Dance: How do they do that?

In the shadows prowls a man in a dark suit. He circles his prey and moves in on her with evil intent. But the girl's no victim. She goes nuclear. Fists fly, limbs flail, heads shake with such force as to empty the skull of teeth. What begins as an assault becomes a macabre jitterbug in which neither party will let the other go. He flings her to the floor and she's up and at him: now a homunculus clinging furiously to his chest; now a lethal blade, her Magimix legs threatening to slice him like a puree. If there is a message, it must be this: muggers beware. Hell hath no fury like a Montreal body-hurtler.

The French Canadian Edouard Lock has been developing this ballistic dance vocabulary for nearly 20 years, latterly through his company La La La Human Steps (silly name, but one you don't forget in a hurry). The style claims no antecedents, though the girls' pirouettes, slowed down to a sensible rpm, would sit quite happily in ballet. The wrenching to and fro between couples suggests a jive, but not the sort your mother ever danced. And the gymnasium element - skewed mid-air torpedoes, whirring cartwheels - are more akin to high-board diving than anything dared on a hard floor.

Physical risk, precision and speed are taken to a point beyond imagining. Is it possible for a body that's self-propelled to move so fast it's a blur? When La La La opened its latest show in silence at the Peacock Theatre on Tuesday (the final event of this year's Dance Umbrella), the only sound was the furtive fumble of the audience cleaning its specs. But disbelief has a short lifespan, and the snag of the current show - enigmatically titled 2 - is that the choreographer shows his entire hand in the first 20 minutes. Outrageously, in view of the ever-present threat to life and limb, the yawn factor asserts itself well before the end of the hour-and-a-half.

But Lock's crash-dance gains a measure of narrative development by long, interspersed sequences of film. The theme of youth and age is presented on a split screen in unnerving dual images of the same woman (Louise Lecavalier), one in her prime and the other decrepit. We see them engaged in such unenergetic pursuits as drinking soup from a spoon or lying in a bed thinking. So when the pugilistic Lecavalier later appears in the flesh and hurls herself at the ether, we deduce that her kinetic rage is directed at the inescapable facts of life, not male domination as first imagined. Rape, philosophy ... what next? Lock's ballet noir can take any significance he wants to throw at it.

All eight performances are brilliant, but Lecavalier is the company's star. Stocky and muscled like a bantamweight boxer, her platinum hair a bird's nest in a gale, she is the least elegant of the women, but thrillingly feral. When she strikes, you expect her to snarl. Perhaps she does and is drowned out by the loud medley of rock, interleaved with a live baroque harpsichord.

One of the two on-stage harpsichords (they were pukkah ones, I was assured) performs a deafening, distorted riff that you would swear came from an electric lead guitar. It's a miracle of something called DAT, apparently. Don't ask how it's done. Don't ask how any of this show is done. I put it down to voodoo. By all the natural laws of gravity, the entire La La La caboodle should have broken their necks by now.

The superficially more sedate world of classical ballet is not very much safer, according to a recent health conference that was called to expose the high rate of injury (and, more surprisingly, malnutrition) among dancers. Cast lists at the Royal Ballet are regularly scattered with last- minute changes, but the opening night on Thursday of Prince of the Pagodas was particularly badly hit, with only one of the advertised principals actually dancing. If that one hadn't been the divine Darcey Bussell, there might have been a mass walk-out at the first interval, not just the discreet thinning in the stalls witnessed at the second.

To put it baldly, Pagodas is a bad ballet. It's the project Kenneth MacMillan should have resisted harder than he did, for his creative genius was not made to do patch-up jobs on other choreographers' work. The original was by John Cranko in the Fifties, in collaboration with composer Benjamin Britten, and it flopped. But the musician in MacMillan could not see Britten's only ballet score go to waste, so in 1989 he re-choreographed it - doomed by its unalterable closeness to Cranko's scenario.

You can't invent fairytale - that was both men's mistake. Prince of the Pagodas throws together scraps of King Lear with Beauty and the Beast, adds a slice of faux-orientalism and comes up with a cut-and-paste sequence that would look flimsy even in a child's colouring book. MacMillan's oddly old-fashioned staging adds to the cardboard-theatre feel, with the corps de ballet lined up at the sides of the stage twiddling their thumbs. And John Georgiadis's set undermines the entire oriental premise of the piece, with his mini- Windsor Castles in place of pagodas.

The interest lies in the two ballerina roles - the Princesses Rose and Epine, the one all Flower Fairy goodness, the other (splendidly danced by Christina McDermott) all spite and jealous flashing eyes - though what girl wouldn't be a bit prickly when her sister gets a pretty name and she's called Thorn? There is a lovely spot of impressionistic movement for a twitching green salamander (Stuart Cassidy's Prince transformed by a spell), and the gamelan sections of Britten's score are glorious.

But in the end, Pagodas is Darcey's ballet (it was the one that shot her to stardom at 20) and, if nothing else, offers audiences generous stretches of time in which to admire how beautifully this dancer is put together.

`Prince of the Pagodas': ROH, WC2 (0171 304 4000), Mon & Wed, then in rep to 2 Dec.