The Mars Volta deserve our gratitude. Not only for providing employment for disgruntled ex-members of At the Drive-In, but also for saving two of the most preposterous hairstyles ever to be shaken to a pulsating, military beat from enjoying a purely mythical status. They play prog-rock so no one else has to.

Wrapping their Led Zeppelin leanings around free-form jazz and electronic fumblings, the band have resurrected that strange beast, the rock opus debut album. On De-loused in the Comatorium, the songs blend and blur as snarling guitar solos snag gentle keyboard melodies with enough aggression to keep old fans rioting. Singer Cedric Bixler and guitarist Omar Rodriguez experiment to such a degree that they appear to be dallying with prog-rock for purely intellectual reasons.

In the studio, that is. Live, with the evil ghost of Yes whispering in their ears, Bixler and Rodriguez twist, lurch and shout. Bixler - he of the Robert Plant voice and Ginger Baker hair - swings his mic into the air before jumping to his knees to the screeching notes and vocal gymnastics of Son et Lumiere. As he attempts a strange half-handstand, he is joined by the Afro-heavy, jolting figure of Rodriguez, who swings his guitar around his neck before engaging in some slippery, Mick Jagger-type swaggering.

Bubbly keyboards melt into swathes of Hammond organ as Rodriguez's squelchy notes pierce the atmosphere of incomprehension. The urgent punk of Inertiatic Esp sticks to the sweet-and-sour formula, falling to a deep softness before a yelling Bixler shatters the melancholy. Each 10-minute epic is smothered in self-indulgence. Each instrumentalist shows off in a solo spot, with bassist Juan Alderete adding sexy funk to the sterile rock while Bixler looks on, content to emote meaningfully and swing the stage lights around his head.

But the dramatics don't make for drama. Essentially, the Mars Volta are a good rock band burdened by their desire to be different. In trying so hard to be enthralling, they end up excruciatingly boring. They have got to either play down the prog pretensions or fire up the pyrotechnics.