Polica, Shepherd's Bush Empire, London

"I'm nervous," confesses Polica frontwoman Channy Leaneagh. “That's why I'm having a rough time. There's a lot of you here. I'll try to improve.” As audience interaction goes, it's not the most reassuring.

It's also oddly unnecessary. Every time Leaneagh stops to tell us how “out of sorts” the American four-piece are, there's a murmur of dissent from the audience. It doesn’t seem a disaster by any means. Maybe Polica are thrown by the way that no-one's really moving; sure, their music is dark and moody and minor keyed, but there are also bracing beats, groovesome bass guitar, and spiky melodies that should catch the ear and twitch the shoulders.

Leaneagh tries to make up for it herself; she dances around between two little stages on which drummers sit, almost conducting the action with twitchy hand gestures, inbetween pouring ghostly vocals into a microphone and twiddling with a raft of samples, loops and vocal effects. It's the sort of over-emphatic, slightly uncool shape-pulling you do when your friends have abandoned you on the dancefloor, but for much of the show I'd love to have got up and joined her.

They've only released one album, last year's Give You the Ghost, aptly titled given Leaneagh's haunting vocals. Playing live, with a bass guitar and two separate drum kits, their music takes on a warmer, more three-dimensional quality, roughing up the record's auto-tuned smooth edges. 'The Maker' begins slowly, before rippling cymbals turn into full-blown, crashing double drums. 'I See My Mother' has a swampy texture and serious stomp, the percussion staying snappy under Leaneagh's quavering lyrics.

They haven’t got that much material to draw on, obviously, and a few new tracks are very much cut from the same cloth. There are longueurs in the set – slower-paced, meandering numbers can drift from woozy to snoozy – but there are enough with real hooks to keep things jogging along.

'Happy Be Fine' – with the plaintive, repeated line “I need some time to think about my life without you” - showcases how gorgeous Leaneagh's voice can be (she nails the high notes), as does an unaccompanied encore of the traditional 'When I Was a Young Girl'. Notably recorded by Feist not so long ago, Leaneagh proves the Canadian singer's got competition when it comes to straddling the pretty/eerie line. Yet even on this, the rhythms and stresses somehow sound very Polica. So what's Leaneagh so nervous about?