Musicals based on movies are so de rigueur that it’s ho-hum, here comes another one, bring on the next. But a musical based on a documentary? Now there’s a reason to do a double take.

The 1975 “Grey Gardens” film fascinated the public with the true-life tale of the two Edith Bouvier Beales — Big Edie and Little Edie — the socialite mother and daughter whose American fairy tale crumbled before our eyes.

Their path of broken dreams led to a Tony-nominated musical with tour de force roles for actresses at three ages. “Grey Gardens” has been scarce since its Broadway run in 2006-07, but now is exquisitely revived by Pittsburgh’s Front Porch Theatricals, with a perfectly cast Daina Michelle Griffith leading the way.

The former Post-Gazette Performer of the Year played another woman on the edge in “Next to Normal” on this same New Hazlett stage. Now she inhabits the dual roles of young Big Edie, as her aristocratic life takes a devastating turn, and later as Little Edie, mired in a destructive symbiotic relationship with her elderly mother.

Ms. Griffith morphs from the sharp-tongued, Big Edie, with flowing red hair and an insatiable need to be the center of attention, to the eccentric Little Edie, encased in a hijab-like scarf for all of Act 2 and going on endlessly, with a Long Island-New England cadence that falls uneasily on the ear.

It’s all the more poignant when Ms. Griffith brings out her sweetest vocals for “Around the World,” which includes the summation lyric, “When you live off mother you can't be free.”

The songs by Michael Korie and Scott Frankel can cut deep, and they can capture the time and character to a T. The second-act opener, “The Revolutionary Costume for Today,” is a good time with a purpose. It brings us forward in time from the 1940s to the ’70s and reintroduces Ms. Griffith as the transformed Little Edie, now a woman in her 50s.

Doug Wright’s brilliant script re-creates two women with outlandish exteriors and infuses them with a desperate sadness and neediness — embodied in all their tragic and often hilarious glory by Ms. Griffith.

The Big Edie of the first act grows older but no less stubborn and needy. Ms. Griffith tag-teams the role to the equally effective Beth Johnstone Bush, a private voice teacher at Point Park University’s Conservatory of Performing Arts who is unrecognizable under a heavy wig and glasses. Ms. Bush’s elderly Edie is mostly bedridden but still picking at the scabs of her daughter’s unrealized dreams.

The revelation for Front Porch audiences is Kaylie Mae Wallace, a West Allegheny High grad, Gene Kelly Award nominee and a rising sophomore at the University of Michigan.

Ms. Wallace plays Little Edie at the height of her society triumph — her about-to-be announced engagement to Joe Kennedy Jr. (Daniel Mayhak) — and sudden fall. The relationship, we’re told, is yet another victim of her mother’s sabotage, in an atmosphere where her grandfather (Bill Crean as Major Bouvier) constantly commands that she marry well.

The show as it leads up to this devastating event does what the documentary could not — it journeys back in time, to when the Beales were in their prime, and posits a theory of the day of their fall from grace.

How well Little Edie even knew Joe Kennedy is debatable. In real life, she left her mother’s home in the Hamptons for New York City, where she enjoyed flings as a model and cabaret performer before returning home to care for her mother. And there they both stayed, in a symbiotic downward spiral.

The once grand mansion known as Grey Gardens mirrored their decline, and mother and daughter eventually lived in flea-ridden filth, among dozens of cats, with the county trying to evict them from their derelict home.

Chad Elder is a strong presence as a witness to the Beale women’s fall. He plays George Gould Strong, a kept man who copes with drinking while accompanying Big Edie in her singing — a need she fulfills to her daughter’s unending embarrassment.

Singing for her nieces — Clara McGough and Lucia Williams as the young Lee Bouvier Radziwill and Jacqueline Kennedy Onassis — Big Edie prepares an unbelievably offensive song, met with the appropriate horror by the Beales’ “servants,” as Big Edie calls them, Delana Flowers and Ryan Jackson. It’s almost as much fun to watch their expressions as it is to watch Ms. Griffith let loose with comedic energy.

Director Robyne Parrish has assembled a fine cast and puts them through their paces — most play dual roles, at least. The scenic design by Johnmichael Bohach, in collaboration with lighting designer Andrew David Ostrowski, transforms a mansion in its heyday from one gone to seed with a flip of a switch.

When the documentary filmmaking brothers Albert and David Maysles found the Beales in their later years, facing eviction from a house infested with bugs and filled with garbage, mother and daughter also were caring for dozens of stray cats. All that should be said is, the cats are present and accounted for, and in an ingenious way.

Most musicals today end with a song of hope or an encore of celebration, and plays may fade enigmatically, leaving the audience in a state of wonder. “Grey Gardens” ends with a question and answer from daughter to mother that is brilliant in its simplicity, a devastating unhappily ever after to an American family tragedy.

Sharon Eberson: seberson@post-gazette.com or 412-263-1960. Twitter: @SEberson_pg.

First Published: August 20, 2018, 3:57 p.m.