Shawn Colvin, Union Chapel, London <!-- none onestar twostar threestar fivestar -->

Shawn Colvin is a star in the US: a triple-Grammy winner and the voice of Christian rocker Rachel Jordan on The Simpsons. Her UK fans are few, but devoted. She cuts a striking figure this evening: black leather boots, olive puffball dress and cropped shock of auburn hair. This is a small venue for her to be playing a solo acoustic set, but then the 50-year-old was playing Bleecker Street bars until she released her first album in 1989, at the age of 33. She's used to intimacy.

The set comprises songs from her new Nonesuch album, These Four Walls, plus requests of audience favourites. At concerts, she says she strives to create a "melancholy limbo". "I've finally figured this song out," she muses over the intro to the rueful "A Matter of Minutes". "It's about grief." There's a beat, and then everyone laughs.

Her poppy, radio-friendly style takes in disparate Americana - folk, country and rock - and sounds deceptively AOR. The new songs are a typical mix of spry melodies, soaring choruses and polished lyrics. But Colvin's live delivery brings out their hidden shadows. Here, a lover's demands on "Fill Me Up" turns into sinister stalking: "I know where you live / I know where you are / Don't get too close / And don't get too far." It's appalling, and riveting. And there's a distinct chill to tonight's austere version of "Sunny Came Home".

But Colvin isn't one for on-stage crack-ups. "Steady On" is moving here because of the sense of potent emotions being kept in check. And her soulful cover of Gnarls Barkley's "Crazy" discloses without descending into histrionic self-indulgence. On "Polaroids", she sings of being "tough as a whore"; that's a bit strong, but there's an appealing robustness to her. She plays the guitar with muscular dexterity, her voice is forceful, and she dispatches hecklers with an easy authority. Her lyrics' acerbity is wide-ranging, too: she gives the portrait of youthful artistic pretension on "Polaroids" a wonderfully acid bite.

Yet she also plays some vaulting, tender songs: "The Bird" is exquisite, despite being interrupted by coughing. But don't be fooled: she's a wolf in sheep's clothing. Her "limbo" is worth spending some serious time in.