Mittwoch aus Licht, Birmingham Opera Company

Singing camels, paddling trombonists, airborne string quartets and a libretto so barmy it makes David Icke sound like Richard Dawkins. Birmingham, welcome to the world of Karlheinz Stockhausen. The German composer devoted 25 years of his life composing his giant, seven-day, operatic cycle Licht. We in Britain have only ever had the chance to see one segment when in 1984 Donnerstag aus Licht was premiered at the Royal Opera House.

For many, Stockhausen's slide into an unattractive cultish spirituality - comprehensively catalogued in Licht - disqualifies the cycle from serious study. Much of the musical establishment (most of whom were absent at the world premiere last night interestingly enough) distanced themselves from this phase of Stockhausen's career. For Graham Vick and the Birmingham Opera Company to take on Mittwoch and for the Cultural Olympiad to get behind it so enthusiastically was perhaps more than a bit of a gamble. But it paid off.

Virtuosically distributing the six-hour action across every square inch of two vast concrete warehouses, Graham Vick is largely responsible for making it work. He did this not by making sense of the cosmic guff or by shaping it as a mystery play in the style of Carl Orff's late paeans to the Christian firmament (the operas that Mittwoch most resembles) but instead by presenting the work's increasingly deranged scenarios as the descent of a religious cult into madness.

Judge the work on the last 60 minutes and you'd have to conclude that the whole thing was a self-indulgent and ill-making farce

A group of believers arise from among the audience at the start, seemingly called to action by the phantasmagoric electronic mist that is Stockhausen's Mittwoch Gruss (Wednesday Greeting). In distant corners of the warehouse activities of greater and greater oddness are snapped. A fraternity appears to build up. There's argument, ablutions, a man practises his sword skills. A group of heavily pregnant women march in formation behind pillars. 

Following these shadowy beginnings, we are invited to enter the bright daylight of the second warehouse space where it seems the believers have convened a parliament for the First Act. A UN chamber of delegates from around the world sit perched atop a circle of high chairs, their faces caked in the colours of their respective national flags, their subject: love. Stockhausen gives voice and choreography to the delegates, thrillingly releasing the inherent theatricality of the parliamentary act. Ex Cathedra, under their director Jeffrey Skidmore, a choir better known for their excavation of Baroque eccentricities, ululated and chanted with immense power and precision, and conjured a sustainably captivating theatre from thin air.

One of great innovations of Licht is the way Stockhausen finds extended unpitched families for various pitched instruments. In Act Three of Mittwoch this gives rise to a number of heavenly duets, flutes mingle with the sounds of a kindergartern and a goatherd, trombones with the noise of elephants (and in this performance the trombonist himself) splashing about in a paddling pool. Most famously in Act Four a string quartet (the plucky Elysian String Quartet) plays to an ostinato supplied by the rotary blades of four helicopters, within which they sit and perform and circle above the auditorium.

For Stockhausen's former partner in crime, Pierre Boulez, the Helicopter Quartet was little more than a gimmick. "You would have to organise an accident to make Stockhausen's Helikopter-Streichquartett interesting," he insisted. Sadly, I think he's right. It seems that Stockhausen was so overjoyed with the poetic connection that he had made between these two incongruous activites that he appeared to forget to write any interesting music for the segment.

We left behind one mad cult only to find ourselves in another 

More fascinating than the Helicopter Quartet music itself were Stockhausen's instructions. He commands that every step of the string quartet's journey from the opera space to the helicopters and back is filmed and relayed back to the auditorium. It was a nice, clarifying frame that was sadly muddied by the inanities of Radio One DJ and official Helicopter Quartet moderator Nihal, who compered the process "because watching a film of a string quartet on a mini bus would be pretty boring". No more boring than listening to you, Nihal. 

Vick did a little too much in Act Three - asking his community of acting volunteers to laboriously mime the source of each and every electronic sound - and not enough in Act Five, which surely could only have worked by putting the inmates in an asylum. There, at the end of Act Four, Vick's staging ended. The audience were invited to mingle with the cast over the electronic music for the final musical segment, Michael's Farewell. And then, like creepy Alpha Course proselytisers, the volunteers spontaneously began to strike up an awkwardly jovial chit chat with us at the end. We left behind one mad cult only to find ourselves in another.

Judge the work on the last 60 minutes - in which we appeared to be inside the head of Tom Cruise - and you'd have to conclude that the whole thing was a self-indulgent and ill-making farce. But look back to the smoky electronic opening, the well paced theatre of the World Parliament or the holistic sound art of the Third Act and you'd have to be pretty mean-spirited not to acknowledge that this was the work of a genius, whose playful innovations have a lot to teach contemporary opera.

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