Every new piece by Howard Skempton seems like sleight of hand. How can he achieve so much with so little, and how do the slightest shifts in his musical language take on such huge significance? Skempton's Ben Somewhen was introduced by the Birmingham Contemporary Music Group as its latest Sound Investment commission, and the apparent insubstantiality of the music was as teasing as ever. The piece is a musical commentary on a set of drawings of the same name by the British artist Ben Hartley; the audience was given copies of the illustrations, though whether there's a one-to-one correspondence between the 15 charming cartoon-like drawings and the sections of Skempton's single-movement piece was not made explicit.

But the music works in the abstract too, for Ben Somewhen is a sort of chamber concerto for double bass and seven instruments. The bass is never spotlighted, just ever present, whether grounding quirky chorales or underpinning trickling harp and woodwind. It's fragile, often very beautiful music, seamlessly woven together.

Skempton's charismatic creative voice was paired here with Judith Weir's, with the first performances of the two latest episodes in the ongoing series of fables with music that Weir has devised with the storyteller Vayu Naidu, tabla-player Sarvar Sabri and BCMG players. Cultures meet in the tales themselves too - one, Manimekalai, comes from a Tamil epic, the other is the Greek myth of Psyche. Though there are parallels between the two stories, the combination of the words and the music is not always convincing. There are some striking interludes certainly - Weir's horn and saxophone writing in Psyche is typically vivid - and the tabla supplies a clever link between Naidu's narration and the ensemble, but the impression of a grown-up Listen with Mother never quite goes away.

· Repeated on Friday at the University of York (01904 432439). Then touring.