Petit Mal is many things: fantastic, weird, terrifying and hilarious. It's Finnish circus for the post-Jack Ass generation, with a lot more sophistication. Some of the turns are traditional circus acts that have morphed - there's a strong man, a man sawn in half, a lot of clowning, as well as the more traditional trampoline and chinese pole. But they're like jazz tunes, so that they're half way through before you realise what they're based on. And they're all done at once, so you're trying to watch a man balancing so high up you can't see his head, while another walks along decked with 18 tyres. Astonishingly the show only lasts and hour and a quarter but it's at least 4 hours of material packed in there.

The three lads who make up this troupe bring different specialisms. Petri Tuominen trained as an electrician. "I didn't like it," he says with typical dour Finnish understatment. So then he took up circus skills, specialising in the chinese pole. Rauli Kosonen is a good-natured trampolinist and Kalle Lehto started out as a breakdancer. But they all do everything, and there's an undercurrent of upstaging each other: a formidable trampoline routine is cut short when the others have enough and tip the trampoline up, pinning Kosonen against the wall. The lads cooperate in a way that looks like they hate each other.

There's no speech in the show, but there are storylines which come and go. Or perhaps there aren't: Tuominen says "We just provide the symbols and people create the story around them". So it's up to us where Donald Duck and the palm tree fit into things. The clowning is certainly surreal, including a Mountie and his horse, two Elvises trying to dislodge a man from a giant exercise ball, and a trampoline routine as tightly choreographed as OK Go on their treadmills. At one point I realised I was watching three men surfing exercise balls across a stage strewn with feathers. One man, two balls and an inflatable shark shot right off the stage into the audience. No-one seemed to mind. As the show got more and more frenetic I began to worry what on earth they would do for the finale - how could they top everything that had gone before? Of course they had a surprise ready, this time one of perfect serenity.

This is a phenomenal show and it's no surprise it sells out everywhere it goes. I had wondered why they weren't booked at the Playhouse for three nights. But having seen the show (and Tuominen's scar) I can see how exhausting it is: three night runs would flatten the boys. Although they've been working on it for two years it still seems fresh, like they're playing. They don't tell anyone not to try it at home. Equipped with nothing more than tyres, planks and gym balls and a desire to play around they've created something totally breathtaking. I could watch it every night. On the bus on the way home we don't just walk to the front - we swing, enjoying the movement round the last bend.