Crystal Castles – Nottingham Rock City, Thursday October 22.

On record, Crystal Castles are an awkward proposition. Their screechy, scratchy electronica is shot through with a primitive punk rock attitude, resulting in a musical blend which strives to be both uplifting and menacing – but the bratty petulance of their approach can get in the way, reducing the music to a tinny, ugly mess. However, as last night’s storming show clearly demonstrated, if you’ve only heard Crystal Castles on record, then you haven’t really heard them at all.

On stage, the three performers – singer Alice Glass, keyboardist Ethan Kath and their touring drummer Christopher Chartrand – are shrouded in smoke and strobes to the point of near-invisibility. When we do catch sight of Glass, it’s still difficult to read her. She is a mesmerising performer, who certainly isn’t afraid to engage with her crowd – standing on their shoulders, passing round a bottle of liquor, then launching her body onto their outstretched arms – and yet she somehow remains cool, aloof, unknowable.

Vocally, Glass is just as hard to fathom. Buried in reverb, her toneless squeaks and squawks barely count as singing at all – and yet they sit perfectly on top of Kath’s thunderous backing tracks, which add whole new dimensions of power to the indie-electro originals.

It’s this scaling up of the band’s sound which makes the show such a success. Tracks such as Crimewave (from the first album) and Baptism (from this year’s follow-up) are transformed into dancefloor-friendly juggernauts, which are ecstatically received by the mostly teenage audience. (Curiously, certain sections of the crowd mosh even harder to the slower tracks.)

With little to focus our attention on stage, it’s the audience rather than the performers which create the atmosphere. Alice Glass and Ethan Kath are merely the catalysts, giving us no more and no less than we need. On paper, it shouldn’t have worked. In reality, it was an unqualified triumph – perhaps even the gig of the year.