But both fictional Edies are so entrancing as the oldest versions of themselves that the movie’s slow, lengthy detours to the 1930s and 1950s are almost a distraction. Even the brief flashback to the early ’70s, when Mrs. Onassis (Jeanne Tripplehorn) is driven by the tabloid exposés of her relatives’ living conditions to visit them at Grey Gardens and finance repair work, is a little long. The acting is compelling, and the costumes are sumptuous, but the staging is static, too “Masterpiece Theater” for the story at hand.  The Beales are far more fascinating for what they became than what they once fleetingly were; Ms. Lange and Ms. Barrymore easily play eccentric beauties, but they are even better in the more complicated roles of crazy cat ladies.  Any reinterpretation of a cult film that has almost as many memorable, and often re-enacted, lines as “Casablanca” is hard, and the mimicry has to be impeccable and subtle. Ms. Barrymore is tested first, since the HBO movie opens with a scene, shot in grainy stock that evokes the documentary’s 16-millimeter footage, showing Little Edie, in her mid-50s, dancing in white Minnie Mouse shoes and a long scarf hiding her bald head, twirling a small American flag to the Virginia Military Institute marching song. Edie, who as a debutante modeled, sang and wrote poetry until she was brought to heel by her family and her own fragility, held on to her performing fantasies well into old age.  All it takes is one shot of Ms. Lange, lying in bed wearing L.B.J.-vintage eyeglasses, her hair white and scraggly and her face and neck wreathed in wrinkles, to know that Big Edie is well and unflinchingly represented.  By the time Big Edie warbles to a recording of her own voice and reminisces about her days as a society matron (“I had a terribly successful marriage,” Big Edie says. “I never threw anything at Mr. Beale, never. I never had words with Mr. Beale at all.”), it becomes very difficult to keep the line between the documentary and the movie, awfully difficult.  The Beale voices are hard to get right, because both Edies had their own way of talking that was at once refined and strident. Big Edie spoke with long A’s and a semi-British lilt, whereas Little Edie had a voice like an irregular heartbeat, which echoed her irregular personality. Even Christine Ebersole, who won a Tony playing both roles in the musical, had trouble holding on to little Edie’s timbre. (In the YouTube video of Ms. Ebersole singing the showstopper “The Revolutionary Costume for Today,” she sounds less like a graduate of Miss Porter’s than like Adelaide in “Guys and Dolls.” )  Ms. Barrymore, dressed in that “revolutionary” costume — dark skirt pinned together over shorts and pantyhose— re-enacts the scene from the documentary almost word for word (“Mother wanted me to come out in a kimono, so we had quite a fight”) not just well, but affectingly.  The documentary exposed a power struggle between two women — the controlling, needy mother and the needy, easily controlled daughter — that was part Greek tragedy, part French farce. The Maysleses’ film, however, was really Little Edie’s vindication, a light shined on a blinkered life lived in the shadows of a more willful personality. The movie also champions Little Edie, but Ms. Lange is so seductive as Big Edie that she keeps tugging the spotlight in the mother’s direction.  Both actresses artfully trace the arc of their characters’ unfulfillment. Ms. Lange weaves some of Big Edie’s youthful charm into the gnarled narcissism of old age; even as a young and stunning debutante, Ms. Barrymore’s Little Edie is flecked with a hint of the jangly unsteadiness of her later life.  Some of the best lines from the documentary are left unsaid. (Little Edie scoffingly refers to East Hampton as a “mean, nasty, Republican town,” but doesn’t recite the documentary’s most famous phrase, “They can get you for wearing red shoes on a Thursday.” ) The HBO ending is far more cinematic and cathartic than the documentary’s elliptical closing shot.  But there is enough of the real Beales in this movie to please even avid fans. And there is enough of a movie to entertain viewers who have never once described a friend, a place or a mood as Grey Gardens.  HBO, Saturday night at 8, Eastern and Pacific times; 7, Central time.  Directed by Michael Sucsy; written by Mr. Sucsy and Patricia Rozema, based on a story by Mr. Sucsy; Lucy Barzun Donnelly, Rachael Horovitz and Mr. Sucsy, executive producers; David Coatsworth, producer. Produced by HBO Films.  WITH: Drew Barrymore (Little Edie Beale), Jessica Lange (Big Edie Beale), Malcolm Gets (George Strong), Daniel Baldwin (Julius Krug), Ken Howard (Phelan Beale) , Jeanne Tripplehorn (Jacqueline Kennedy Onassis), Arye Gross (Albert Maysles) and Justin Louis (David Maysles).
“Grey Gardens,” to be shown on HBO on Saturday, is a retelling of the Beales’ tale that blends material from the documentary with flashbacks to the two Edies in their glory days.