In an era in which women jazz singers are inclined to whisper, wheedle and wilt, Miami-born Carmen Lundy maintains a restless, prowling determination. A gracefully expressive woman, whose voice seems too deep for her wiry frame, Lundy is an immensely sophisticated performer who can trigger every audience reflex in the book. Yet she chooses not to, reworking her own rather private originals and familiar songs.

Lundy is opposite the Jazz Hearts, a breezy townships-and-Latin local band that struggled a little on its opening night but delivered some catchy themes and good solos from the leader, Louise Elliott (particularly on flute), fiery trumpeter Claude Deppa and silky trombonist Mark Bassey.

Then Lundy took to the stage, with her familiar demeanour of someone hovering and perplexed. But all hesitancy vanished when she sang. She opened with Spring Fever, stretching the melody between deep, purring sounds and upper-register swoops.

Lundy's favourite vocal territory is the middle and lower range. She followed Spring Fever with a song of gratitude for childhood, in which any hint of schmalz was banished by an urgent, stamping mid-tempo groove. Young pianist Robert Glasper, a McCoy Tyner-inspired player, delivered the first of several solos that declared the arrival of a new keyboard force. Glasper sketched a pristine, haunting, classical-sounding counter-melody under Lundy's majestic account of Nature Boy. Bassist Curtis Lundy complemented his sister's lustrous sound with deep, growling long notes, and drummer Victor Lewis was as succinct as he ever is.

Occasionally, you wish Carmen Lundy would just get down and stomp a little, but if she lives in a world of her own, she's pretty hospitable about it.

· Carmen Lundy and the Jazz Hearts are at Ronnie Scott's, London W1 (020 7439 0747) until Saturday.