The harp has never been the most rock'n'roll of instruments. Save for a notable appearance on the Beatles' She's Leaving Home, it was only Brian Wilson who saw the possibilities. Until now. Step forward Joanna Newsom, classical harpist and burgeoning queen of alt-folk.

Despite having grown up in Nevada City and now firmly ensconced in the San Francisco scene that has spawned the similarly nostalgic and odd-sounding Devendra Barnhardt, 22-year-old Newsom has a twang that's straight from the Appalachian mountains.

Influenced by bluegrass and blues, her debut album, The Milk-Eyed Mender, sounds like a lost soul wandering around Narnia. Her songs are dark nursery rhymes, but her childlike take on the world is no act. "My dad's here," she says. "He's come a far far away from the horrible horrible things going on in the United States," she continues, as if about to read an especially grim fairy tale.

Newsom is a magnetic, mischievous presence. Her fingers deftly run up and down her towering celtic harp, adding drama to the dizzy sweetness of Cassiopeia. Eyes skyward, as if taking instruction from some divine source of inspiration, she rests her head close to her harp, as though nestling into a lover.

Then there's that voice. A combination of Cat Power, Björk and a pre-pubescent Bonnie Langford, she caresses and squashes words with abandon. Newsom rolls her tongue around her eccentric poetry and knowing prose with all the relish of a child licking an ice-cream. Often she shrieks like an attention-seeking toddler, before turning passionately maternal for the antiwar lullaby What We Have Known.

Her vocals take some getting used to; you need to retune your ear to make out her meaning. But it's worth it. From the exotic En Gallop to the dreamy escapism of Sadie, classical rhythms rise and fall around Newsom's fractured voice, turning heartache into fantasy.

· At the Rescue Rooms, Nottingham, on November 20. Box office: 0115-958 8484. Then touring.