Like all the best bands, Architecture In Helsinki appear to have parachuted into this world from another, far freakier dimension. They claim to have met at a Tupperware party in Melbourne and looking at the eight of them as they mess about with rubber hands and trombones and assorted bits and pieces presumably lifted from their favourite charity shop, you can just about believe them. If the cult Aussie soap "The Secret Life Of Us" had been set in a St Kilda squat populated with art school drop outs, hip hop stoners, literary slackers and the kids from the local cake shop, then it might have been half of what we're presented with here.

For the most part, exactly what they're up to is a mystery. The show starts with a darkened stage and a tolling bell, giving way to a serene yet otherworldly "Star Trek" theme-style female vocal. The band themselves have been hiding under their keyboards and slowly stand to add trombone and tuba to a series of melodramatic crashes and surges. Then a sweet tinkly piano takes over with singer Cameron Bird trilling about "walking on the moon with your stalker" as the band ring bells, hit cowbells, shake things and general make a rag bag of noise. Then a frantic beat kicks in and the two front girls scream riot grrl yelps about something or other. Then it's back to tentative oddity. Then more yelping. Then more nonsense. Ad lib to fade.

That this is clearly one huge in-joke is obvious from the start. The band never fail to make each other laugh while they're arsing about in the name of music, going "haaa!" in the mic one by one or popping their fingers into their mouths. And it's hard to escape the notion that the best place to see AIH would be at a basement party back at that squat in St Kilda, songs being stopped halfway through so someone can get a drink or skin up. But, crucially, it's also an in-joke that you feel in on, a private party that you've been invited to, even if you didn't quite realise that it was fancy dress and you showed up in your work clothes.

At times they resemble The Go! Team, if they tried to knock together their Supreme Team Sampledelia without having access to any samples. Songs like "Do The Whirlwind" and "Wishbone" draw on the same core sources, blending 80s NYC electro and hip hop with K Records indie pop, but favour a host of offbeat meanderings and tangents instead of simple, dancefloor euphoria. Often it feels like the band have taken the pop song apart to see how it works and are having trouble putting it back together, tunes heading off in unexpected directions and Bird getting extremely worked up over something utterly incomprehensible.

You'll either find this all wildly endearing or hugely irritating. Not for nothing do they sometimes resemble The Sugarcubes or an outtake from "The Rocky Horror Picture Show". But I'm smitten, not least when they finish off with a cover of Roxy Music's "Love Is The Drug" that buzzes with youthful exuberance and the sheer, unhinged confidence of true originality. As someone far wiser once said: "Lumber up, limbo down, the locked embrace, the stumble round, I say go, she say yes, dim the lights, you can guess the rest." If only you could.

Ian Watson