In concert, there are no half measures with Joan As Police Woman. An artist who keenly feels every emotional pinprick, Maine-born Joan Wasser seems to spend this set either laughing edgily or blinking back tears, making an evening with her something of a rollercoaster. Her openness packs a punch few other songwriters achieve; when she's stuck into a song, inhaling raspily between each eviscerating verse, you wonder why on earth she's not as renowned as her friend Antony Hegarty, who booked this gig as part of his curation of this year's Meltdown.

On the other hand, witnessing her zigzagging moods is a little draining, and despite the evident sincerity, it's hard to not wish at times for a bit of stiff upper lip. The audience could show her a thing or two in that regard: when she precedes Human Condition by giggling: "This is about being obsessed with humanity and falling in love with every single person on the train – do you do that?" she's greeted by an Olympian display of British reticence.

But it all makes for a unique show that solidifies her reputation as a singer, pianist and guitarist of substance. Sporadically accompanied on guitar by Antony and the Johnsons member Rob Moose (and, on the stately, crushing To Be Lonely, by the Johnsons' string trio), Wasser sinks deeply into each song. Her current direction, as such, is loungeish soul – exemplified by the smooth-sided Stay and Kiss the Specifics from her last album The Deep Field – but she's also a marvellous torch singer. A cover of Sandy Denny's No More Sad Refrains ("One of the saddest songs ever written," she whispers), in particular, is so smoke-stained and blue as to be an entirely new composition. Finishing with What a World, which drifts with beautiful abstraction for weeks, she emits one last caffeinated laugh, and leaves to enchanted applause.