The programme for Patsy Cline: A Musical Tribute informs you that 'Patsy Cline's music and lifestyle is hip to contemporary youth audiences', a statement that in its unconscious fuddy-duddiness sounds like the answer to a question from a High Court judge ('Is the court to understand that this Patricia Cline is a popular vocalist?'). Still, it's a valid point: perhaps by virtue of her early death, Cline is among the few country singers that non- country audiences think it's cool to like.

Whether the show is in a position to cash in on this kudos is open to doubt, though, hampered as it is by a script - written by the inappropriately named Johnny Worthy - that fails dismally to live up to its subject.

The structure is simple: the narrator, the likeably mild-mannered George Hamilton IV, relates Patsy's story, in more or less chronological order, from her birth in Virginia in 1932 to her death in an air-crash in 1963 (the opening number, 'Always', fades into the eeeooooowww of the plummeting plane). In between, characters in her life - including Loretta Lynn and Brenda Lee - step forward to introduce themselves, say what Patsy meant to them and sing the odd song.

The connection between songs and life is occasionally made explicitly intimate - as when Patsy's rendition of 'I Fall to Pieces' is interrupted by her second husband, demanding that she should be a real wife to him. Just as often, though, the link is mind-bogglingly tenuous. After Patsy's successful debut on the Grand Ole Opry radio show, for instance, Hamilton remarks that not everyone went down so well first time - this turns out to be the cue for an Elvis impersonation.

Even when the narrative isn't off on a tangent, it manages to skate over the things that are individually interesting about Cline's life in favour of universalisable music-biz cliches - she wows sceptical promoters at auditions, is exploited by unscrupulous management, fights snobbery, finds her marriage threatened by success. Important details are omitted altogether, or introduced so casually that they become difficult to fit into the story. When Hamilton mentions the conflicting pressures of work and children, you do a double-take - children? When did they turn up?

Given these vacuums, it's not surprising that Sandy Kelly, for all the gutsiness and aplomb of her vocal impersonation, can't do much with Cline's character. We know that she's supposed to be a feisty lady with an eye for the men, and Kelly wears a smirk that certainly fits those characteristics; but attempts to show off this feistiness fall miserably flat. At her first radio audition, the producer tells her he didn't catch her name; quick as a flash she snaps back, 'Well, I didn't throw it' - small gasps of outrage and appreciation from surounding cowboys, while Hamilton purses his lips and gives the audience a conspiratorial sideways glance. Other than that, Cline's main trait is a habit of addressing all men as 'Horse'.

This isn't the place, either, to go for close analysis of Cline's technique. The nearest we get is Hamilton's remark that 'she had that certain special something that Grand Ole Opry audiences just took to their hearts'.

Still, what you come here for is the music: and this, Kelly aside, is terribly variable - not all the sizeable cast are equally at home with country idioms. But in the climactic group of songs (leading up to a mass rendition of 'Will the Circle Be Unbroken?' and Kelly's smoochy solo 'Crazy'), they show a zest which, extended over the whole two and a half hours, would make this unmissable. As it is, you worry that the real patsy here is the audience.

'Patsy Cline' is at the Whitehall Theatre, London SW1, until 15 Oct (Booking: 071-369 1735)