Gaiety Theatre, Dublin ****

John Carney’s endearing film from 2006 may have been transformed into a Broadway show but neither version could be easily described as a musical. A better description might be “a love affair with music”.

The story, about a luckless Dublin busker and a remarkably direct Czech pianist, is passionate and chaste: they make beautiful music together but it goes no further.

Enda Walsh’s nimble and clever book demonstrates just how sensitive this version is to its source while wisely cutting through any treacle. It isn’t easy – musicals are not known for subtlety. But director John Tiffany enjoys the artificiality of the form, creating a cast of able performer-musicians and setting the action in a Dublin bar, designed by Bob Crowley, which stands in for anywhere. Some will bristle at an Irish story that can’t leave the pub, but it gives the absorbing show an intimate, conspiratorial quality, like a session during a lock-in.

It also hastens through plot contrivances with cheering brio: Guy (Declan Bennett) and Girl (Zrinka Cvitesic) “meet cute”, and when she learns that he fixes vacuum cleaners, her broken hoover appears from nowhere. In the wrong hands Girl would seem like an exotic, enabling cipher for our laconic, passive Guy, but Cvitesic lifts the part with a send-up of eastern European fatalism (“Is she dead?” she asks of Guy’s ex-girlfriend), and tolerable quirkiness.

Walsh reconceives the film’s minor parts as a motley crew of comic support characters – essentially The Producers meets The Commitments – where Aidan Kelly is most amusing as a music-shop blowhard. But his focus on an immigrant Czech community serves the story better, where families argue fiercely about characterisation on Fair City and hope, quite sincerely, for a better life.

Such hopes animate Glen Hansard and Marketa Irglova’s music, too – here songs don’t convey plot, like a traditional musical; they let timid characters voice their dreams. In one masterful moment, Guy is heckled introducing Gold in which “to live, you have to love” (“Oh sweet Jesus . . . ”) and it short circuits all natural cynicism.

It helps that Bennett, whose often unintelligible Dublin accent is clearly intended for a forgiving West End audience, isn’t quite as throatily emotive as Hansard, that movement director Steven Hoggett often corresponds with stylised gestures of trapped people slipping their bonds, and that music director Martin Lowe knows the elevating effect of a bed of violins for Falling Slowly, or the stunning a cappella harmony of Gold’s reprieve.

With one beautifully simple stage picture of a constellation of city lights, it’s tempting to see Dublin, like Guy, also encouraged to pick itself up and reach higher. That may be a fairytale, as the title has always known, but it’s still a captivating and charming elaboration to once upon a time.

Until March 9th