Back in 1959, during the golden age of the Broadway musical, American composers developed the confidence to tackle some of the weightiest dramas of the previous 50 years. It was the era of My Fair Lady, Guys and Dolls and West Side Story, and musicals suddenly had the scope to become as thematically daring as they chose to be.

How else to explain librettist Joseph Stein's ambitious decision to tackle Sean O'Casey's dark masterpiece, Juno and the Paycock turning it into a song and dance musical? A tragicomedy with a body count, from the beginning it wasn't exactly standard Broadway fare.

Juno, with a score by the brilliant but relatively unsung composer Marc Blitzstein, incorporates Irish traditional themes and melodies into a full on Broadway spectacle. This was about as innovative as a musical could get at the time, and the daring composer jumped at the chance to expand his range. Authentic jigs, waltzes and reels share stage time with the semi-operatic crowd pleasers carefully crafted to make you weep.

With all of its daring elements in place, the show didn't fare well in its original 1959 run. First of all, its two main stars - Shirley Booth and Melvyn Douglas - were at best indifferent singers, and Blitzstein's score requires barnstormers.

Secondly, there was the issue of the tale itself. The mayhem of the Irish Civil War was never likely to become the feel-good hit of the season, and there's no question that the show suffered at the hands of its mournful plot.

But this month the City Center's "Encores!" concert series has revived the admirable old musical in an abbreviated adaptation directed by Tony winner Garry Hynes that showcases Blitzstein's atmospheric Irish score, magically transporting audiences to Dublin for the entire two hours of the show.

With the celebrated Broadway singer Victoria Clark as Juno, the show receives the creative shot in the arm that the original production lacked. As she demonstrated recently in The Light in the Piazza, Clark is a walking master class in musical performance, as enchanting an actor as she is a singer, and she steals almost every scene she appears in.

The strong cast is also well served by the redoubtable Rosaleen Lenihan. Gifted with a voice that's so expressive she can convey complex emotional states in a single word, Lenihan is a joy to watch in the role of Maisie Madigan, the gamey widow with a song in her heart and with an eye for men and whiskey. She is also the heart of the show, giving voice to the private concerns of the community with authority and compassion.

Hynes has elected to always stay true to the spirit of O'Casey's play, scaling back from too much frivolity to remind us of the essential seriousness of the plot. When Juno Boyle's family discovers they're about to inherit an unexpected windfall the musical kicks into gear with singing and dancing to match.

But at all times Hynes keeps her eye on the harsh realities of Dublin tenement life, and the painful realities they barely conceal. British soldier raids interrupt celebrations; happy gatherings give way quickly to the harsh realities of the Civil War.

The musical's conclusion is a theatrical coup, underlining the difficulty of bringing this story to the Broadway stage. War is hell, we're reminded, and sooner or later all of its patriotic songs end in silence and that silence will break your heart.

As Captain Jack Boyle, the strutting "paycock" of the musical, Conrad John Shuck is spectacularly miscast. Playing against type, Shuck makes the best of his material, but the humor and pathos of his character elude him from start to finish.

Clark is left to invest their unlikely relationship with the necessary human warmth - and this she does valiantly, but Captain Jack's abandonment of his family in the second act loses its impact since Shuck is so obviously adrift in the role.

The score of Juno is charming but for the most part instantly forgettable, seeming to melt away into the air moments after you hear it. One song, though, is outstanding, the Count John McCormack parody Bird Upon the Tree.

So plaintive and otherworldly that it almost belongs to another show, Clark as Juno and Celia Keenan-Bolger as her daughter Mary bring the night to a standstill with their harmonics and with the promise of this musical abundantly fulfilled.

Juno is playing at City Center, 131 West 55th Street in New York, through Saturday. Call 212-581-1212.