Param Vir's Euripides opera has had a stuttering history. It was originally commissioned by the Aldeburgh festival and Almeida Opera, but was not finished in time for the scheduled premiere in 2000; only part of the score was heard then. Music Theatre Wales took over the commission and is now presenting the completed work, directed by Michael McCarthy and conducted by Michael Rafferty.

If only their persistence and faith in Vir had been rewarded. But Ion seems no more convincing now than it did as a torso in Aldeburgh - no more musically memorable, no more dramatically necessary. Vir's score never shows why he was drawn to the play in the first place, why this story (Ion, shrine-minder at Delphi, is reunited with his mother Creusa, while discovering that he is the son of Apollo) matters to him and should, through his music, be made to matter to us.

David Lan's libretto veers between high-flying imagery and throwaway vernacular, and sometimes shows little sense of what is singable and what is not. Vir's word-setting is more declamation than anything else, though the appearance of Athene at the end - to tell us everything always turns out well if you trust Apollo, forgetting that he caused all the problems in the first place - sparks an outburst of coloratura that is meant, I'm sure, to be satirical or ironic. This is intended as a comedy, after all, though laughs are few, and Vir's music lacks wit. Some of the understated instrumental writing is striking, but there is no mutual dependency with the drama; setting the play to music (less than two hours of it, though it seems much longer) adds nothing.

Music Theatre Wales does its usual efficient, economical job on a work that demands a cast of 11 and an ensemble of 17, with Michael Bennett's Ion and Rita Cullis's Creusa the strong protagonists. But nothing can disguise the failure of Vir's score to get to grips with its subject matter in a genuinely operatic way.

· At Gala Theatre, Durham, on Monday. Box office: 0191-332 4041. Then touring.