Anet Mook's voice immediately commands attention. Even on record, she hoarsely screams and reaches rare levels of catharsis. Comparisons with Courtney Love have abounded but for sheer visceral impact it's not fanciful to describe Mook as a half-pint sized, female Black Francis.

Her fellow band members are no slouches either. Cay's debut album, Nature Creates Freaks, combined granite riffs with the unorthodox tunings of Sonic Youth and hinted at the influence of post-rock maestros Slint. So there was considerable expectation as they ambled on stage and launched into a blistering Princes and Princesses. Mook was in fine form, presumably having swallowed a cocktail of ground glass, absinthe and 200 Park Drives in preparation.

It was the perfect soundtrack for the moshpit to collect bruises as limbs collided and drinks were thrown in the air. During Nature Creates Freaks, however, Mook jerked away from the microphone and Nicky Olofsson cast off his guitar as the song hobbled to an untidy conclusion. A stage-diver had spilt beer on their equipment.

The interruption fatally punctured Cay's impetus. A batch of new songs displaying their sound's increasing subtlety were not ideal for the occasion, and were hindered by a lack of stage presence: Olofsson cut a statuesque figure and Mook shuffled undemonstratively around the stage. Bare-chested drummer Mark Bullock, attacking his kit as if fulfilling a serious vendetta, provided a more dynamic focal point.

They belatedly regained inspiration with the concluding Reasonable Ease in Chilled Out Conditions. Guitars raged then, displaying their grasp of light and shade. The song shifted to contemplative mode as Mook gasped "and when we both come down/and when we're both worn out". It seemed an apt reflection on a night which could have been a triumphant reaffirmation of rock's transcendental qualities but instead offered only fleeting glimpses of Cay's capabilities.

Cay play the Cavern Club, Exeter (01392 495370), tonight, then tour.