Forty-six years after the derailment of Stephen Sondheim's would-be Broadway debut, Saturday Night finally makes it to Boston as the final show of the SpeakEasy Stage Company's tenth anniversary season. Resurrected from the Sondheim archives in the 1990s for productions in London and the US, this surprisingly fresh little musical is now at the Lyric Stage in Copley Square through the end of June.

As originally written, Saturday Night had more characters and called for dozens of singers and dancers to execute elaborate production numbers. Sondheim, himself, cut some of the characters and edited the unfinished book to better suit contemporary storytelling expectations and accommodate the more limited resources of those interested in doing the show today. He completed two unfinished musical scenes, "Montana Chem" and "Delighted, I'm Sure," for the US premiere in Chicago in 1999.

But don't think this show is a museum piece. The Julius J. Epstein book, based on the play Front Porch in Flatbush by Epstein and his twin brother Philip (both best known for Casablanca), tells the story of a third brother who was a Wall Street runner in 1929 and yearned to live on the posh Manhattan side of the Brooklyn Bridge. In Saturday Night Gene, the big dreamer and schemer, convinces his friends to go in with him on a "sure thing." He promises they'll make a financial killing like the elevator boy now living with the swells on Park Avenue. Sound familiar?

I warmed right away to the charm and talent of this young cast, put to good use here by director Will McGarrahan and choreographer David Connolly. There was no question that these guys have been hanging out for years and stand ready to lay down their lives for each other. When we meet Ted, Artie, Ray and Dino (Braden Lybell, Bill Folman, John Michael Dias and Jose Delgado), their biggest worry is "What can you do on a Saturday night- alone?"

We can easily accept that Gene is their ringleader once Jon Mettee gets past "Charm," a song slightly out of his vocal range, and gets comfortable. And David Krinitt adds a delightful contrast as Hank, the steady married friend, offering a glimpse of what they'll all become one day.

The girls in the supporting cast sing their hearts out. Clearly, these Brooklyn gals need a guy as much as their male counterparts yearn for them. Jackie Duffy, as Hank's wife Celeste, functions as a combination den mother and social director. She produces Mildred (Mary Faber) as a last minute date (split four ways) on the first Saturday night. When the two of them come up with Flo (Tara Filowitz) the next Saturday night, the guys readily ante up for half a girl each.

Helen, who sweeps Gene off his feet masquerading as a Southern deb at the Plaza, is played by SpeakEasy veteran Bridget Beirne. A recent Boston Conservatory graduate, Beirne received the Eliot Norton Award for Violet last year and this season has displayed her considerable talents in Floyd Collins, Songs for a New World and her own late-night cabaret act.

Once Helen drops the faux-Southern (expertly rendered in "Isn't It?") and admits to being the daughter of a Brooklyn chicken seller, Beirne has the difficult task of being the one to bring Gene down to earth. She has no trouble getting our attention with her amazing voice, but I couldn't help wishing for a slightly softer sell in the ballads.

Although she succeeds with everyone else, I also think costume designer Stacey Stephens does Ms. Bierne a disservice. While Helen's "going out on the town" getups suggest that they've been put together by a Brooklyn girl of limited means, they look too much like recycled "mother-of-the-bride" outfits for my taste. I'd rather see credulity stretched a bit so Helen can look her best.

The minimal set, designed by Eric Levenson, does serve the piece well. We get the corner of a Brooklyn front porch with the moon (which changes its shape on each of the three successive Saturday nights,) hovering above "like a million-watt electric light." McGarrahan and Connolly are smart enough to confine very little of the action to the porch itself, making good use of the entire playing area for the extended Brooklyn scenes.

Even before the release of the London and NYC cast albums, many of the Saturday Night songs were known to Sondheim aficionados from the compilation score of Marry Me a Little, the Unsung Sondheim CD and other concert and tribute recordings. The score may be early Sondheim, but it's perfectly crafted and amazingly intricate for a 23 year old emulating the traditional forms he would later expand on so freely. And "So Many People" and "What More Do I Need?" have earned their place as cabaret standards.

To the credit of all involved, this production reminds me of Diner, one of my favorite movies. It's proof, to me, that the show needn't stand on its score alone. Saturday Night measures up favorably against other book musicals from any period, be it the '20s of its setting, the '50s when it was originally written, or today in its reincarnation as a small musical, the necessity of invention of the '90s.

Saturday Night is presented by The SpeakEasy Stage Company, Paul Daigneault, Producing Artistic Director, at the Lyric Stage, 140 Clarendon St., Boston (the YWCA building) thru June 30. Performance schedule: Wednesdays thru Saturdays at 8PM; Sundays at 7PM; Saturday matinees at 2PM. Box office phone: 617 437-7731.

See the current theatre schedule for the Boston area.