The second act of "Grey Gardens," according to someone I overheard Wednesday night in the lobby of the Ordway, takes pains to replicate the elements of the 1975 cult-documentary film about the weird Edith Bouvier Beales, who inhabited a decrepit mansion in the snooty Long-Island Hamptons while their niece and cousin was in the White House and elsewhere.

I haven’t seen the film, so I can’t attest to the patron’s claim. But "Grey Gardens" is certainly a weird character study of a musical. It’s about Edith Beale and her daughter, Edie, who went from musical artist wannabes in the 1940s to grumbling, cantankerous reclusives surrounded by filth and flea-infested cats.

But, oddly enough, the adaptation (by Doug Wright) begins as a close-to-spoof of a pre-World War II musical, with songs (by Scott Frankel and Michael Korie) that have the flavor of Coward and Porter. The first-act setting, too, is right out of the dinner-jacket milieu: an estate in 1941 where names are dropped amid witty cocktail banter. When the second-act squalor is revealed, the songs lose the operetta tingle, the voices acquire that adenoidal Long-Island wheeze, and you wonder if the first act was really a fantasy dreamed up by two crazy old ladies.

As the show opens, Edie Beale is about to announce her engagement to Joseph Patrick Kennedy Jr., whose rise to the White House seems like a foregone conclusion — though, as we know, the oncoming war will end that. The Hampton mansion is aflutter as mother Edith, who has been dumped by her husband and now pals around with an unabashedly parasitic gay musician, prepares to throw a bash for the arriving Kennedy clan.

Between solos by the piano, we also meet Edith’s young nieces — sisters Jacqueline and Lee Bouvier, one destined for Camelot, the other for the title of princess. The Beale women’s plans collapse by the end of the act and time shifts forward more than three decades into a kind of pseudo-documentary reality. What a fall from glitter and sheen.

Three strong women make it work

It takes three strong women to put this show over, and the production at the Ordway, a collaboration with Park Square Theatre, has them in Christina Baldwin, Zoe Pappas and Wendy Lehr. Baldwin plays mother Edith as a kind of wounded, self-involved Auntie Mame in the first act and then becomes a twitchy, grotesque Edie in the second act — a fabulous part for any actress. Pappas, a terrific musical-theater singer and a striking actress, is a tragic first-act Edie. And Lehr, one of the treasures of the local theater community, is absolutely raw as the old, invalided Edith.

The show has dream sequences to liven up the second act and a nice crew of hastily sketched caricatures — Richard Ooms as the thundering Bouvier patriarch and (oddly) Norman Vincent Peale, Joshua James Campbell as young Joe Kennedy and a zonked-out hippie, Michael Gruber as the fey, Cowardesque piano player, and child actresses Kacie Riddle and Adelaide as the young Bouvier girls.

The sound system in the Ordway’s smaller McKnight Theater, with its jacked-up wireless microphones and piped-in-sounding music, was annoying to me on opening night, but it worked tolerably well.

In the end, it’s an odd little musical, stacked with name-dropping and quick-sketched characterizations, but also propelled by a fascination that comes from seeing how far afield the human spirit can wander. As it seemingly must, the show ends by drifting away, much like lives wasted.