NEW YORK -- Why is every great musical darker than we recall? And although it's late in the game to be asking, why isn't "Gypsy" named "Rose"?

Maybe it began as the story of how witty, glamorous stripteaser Gypsy Rose Lee emerged out of her ugly duckling childhood, driven by her ferocious stage mother and by her need to escape from her control. But that mother won't be denied: long before she turns the musical's final number into "Rose's Turn," she hijacks the whole musical, bullying everyone around her, driven by a need as great as all vaudeville.

That's the darkness we rediscover whenever "Gypsy" is done well. As with all great musicals, there's an ample array of such other pleasures as comedy, story and song, but it's the anguished heart that drives the whole.

So the story of "Gypsy," in spite of its colorful backstage comedy and the iconic, anthem-rich score by Jule Styne and Stephen Sondheim, is always about who plays Rose, from the original, Ethel Merman, through recent revivalists Tyne Daly and Bernadette Peters, to the performer who was long destined to play her, Patti LuPone.

It's a breathtaking performance, especially admirable in LuPone's willingness to embrace Rose's mendacity, manipulation and obsession. Granted, she has charisma -- you can see why Herbie would fall in love with her magnificent chutzpah and energy. But she's every inch a monster, and don't let her short stature fool you, there's a tall tiger of emotional greed wrapped up in that dowdy exterior. What most makes LuPone's performance great is her willingness to eschew glamour for that dark need. She sings the heart out of the songs, but this is really a tour de force of acting, imposing both the performer's and the character's will on all around her.

Behind the indomitable LuPone is the magician behind "Gypsy," book writer Arthur Laurents, indomitable himself at 90, who is also the director. And I have it from Lenora Nemetz, the Pittsburgh performer who's also no slouch in the indomitable department (see story below), that even well after the opening he keeps working every day, directing the standbys, keeping this huge musical on its toes.

It's big, with a supporting cast that keeps on coming, a backstage panorama of mid-century showbiz, from agent to producer, comic to stripper, wanna-be to never-was.

Fully LuPone's match in emotional truth is Boyd Gaines' Herbie, always a best man, never a groom. The delicacy of his weakness becomes strength. It's a performance of integrity, without a breath of shtick.

Laura Benanti's Louise matches him most of the way. I love the small details through which she conveys her self-sacrifice on the altar of her mother's will and of her sister June's supposed stardom, and I believe her discovery of the strength to stand up to Rose. Only the big sequence where she discovers herself as Gypsy Rose Lee is somehow less than convincing, feeling a bit forced or rushed.

Well it might, since that's the longest time Rose is out of sight, the pause before the storm of her rebellion to come. It's exactly like the long time in that other drama of self-promotion, when Macbeth disappears as young Malcolm discovers himself in England, leading up to their final battle -- and if you think that's an arcane parallel, it's completely appropriate to suggest the drama of Rose's overthrow.

Deprived so long of the spotlight, Louise finally blossoms out of emotional necessity. Ironically, as life delights in being, it's the most repressed, inhibited character who makes an eventual career out of seeming to reveal herself.

Pittsburgh is well represented in support. In addition to Nemetz's dual turn as the wry Miss Cratchitt in Act 1 and the brassy stripper Mazeppa who bumps it with trumpet in Act 2, Leigh Ann Larkin is a dauntingly precocious Dainty June and Tony Yazbeck, a handsome, touchingly hopeful Tulsa.

There's further strength in the other parts of the famous stripper trio, Alison Fraser's daffy Tessie Tura and Marilyn Caskey's comically comatose Electra.

The orchestra is a visible supporting player, occasionally revealed filling the upstage area. For once, we get a proper overture, warming us up for musical glories to come.

That visibility seems odd, but it's in keeping with the backstage nature of the show, and indeed Styne's music deserves this further emphasis. "May We Entertain You" (and all its variations), "Some People," "Small World" ... it's one perfect song after another, leading up to Rose's act-ending signature numbers, "Everything's Coming Up Roses" and "Rose's Turn."

That last title has a double meaning, of course. It's Rose's turn to shine, but it's also her "turn" in the showbiz sense of being her featured number. And that's ironic, since "Gypsy" has been Rose's turn all along.

At the St. James Theatre, 246 W. 44th St.; for tickets, call 212-239-6200 or go to www. newyorkcitytheatre.com