With such an outlandish moniker, you would expect Monkey Swallows the Universe to be reasonably adept at grabbing people's attention. In fact, for much of this gig, their delicate songs, ethereal as a summer breeze, are all but lost in a storm of audience chatter. Conspicuous in the din are a contingent from the band's home town, Sheffield, who cheer lustily at the downbeat chorus to Sheffield Shanty; a group of teenage girls who, true to the band's musical roots, are dressed to party like it's 1986; and one beleaguered chap hissing at people to be quiet. Eventually, he gets his wish.

It doesn't help that frontwoman Nat Johnson is visibly quivering with nerves. "I think I'm having a good time," she giggles, "but my heart is going tick, tick, tick." She appears to find it difficult to raise her voice even above the gentlest melodies played by her bandmates: a drummer, a cellist and a duo who swap, with varying degrees of proficiency, between acoustic guitar, lap steel, violin, mandolin, xylophone and recorder. Johnson's songs may be self-effacing, but listen closely and you realise their winsomeness conceals jagged edges and gritty hearts: they need to be played with confidence for their many layers to be appreciated.

It is not until the audience hushes that the band find that confidence, and when they do, the show is wonderful. Elizabeth and Mary conjures an atmosphere of tense suspicion and seductive drama, while Florence erupts euphorically, its tale of bitter heartbreak deliciously at odds with the enthusiasm with which cellist Andy George bats balloons into the crowd. The band are soon to take a lengthy sabbatical; let's hope they return with a little more of this boldness.

· At the Boardwalk, Sheffield, on Friday. Box office: 0114-279 9090. Then touring.