Director Michael Bennett, who took us behind the anonymous precision of "A Chorus Line" and found it teeming with heartache and theatricality, has gone backstage again for his latest musical, "Dreamgirls," which opened Saturday night at the Imperial Theatre. He doesn't find quite so much this time.

Budgeted at close to $3 million and wildly anticipated on Broadway, "Dreamgirls" is a sleek, fluid spectacle that raises the art of stagecraft several breathtaking notches. But the story it tells, about three bumpkins from Chicago who are molded into a pop singing group not unlike -- in fact, very much like -- the Supremes is rather distressingly trite. It has the sound of Motown, perhaps, but its sentiments are right out of "42nd Street."

This could have been a tough, innovative musical about the record industry, and all the ruthless manipulation and cool betrayal that underlie the glitter of superstardom. But author and lyricist Tom Eyen has bitten off far more than he can digest. He wants to chart the personal and professional lives of the Dreamgirls, their managers, their boyfriends, their composer, plus assorted moguls and performers, some of them on their way up, others very definitely skidding downward. What comes out, however, is truncated and hoary. When he isn't glossing over crucial scenes, Eyen tends to get hung up on the stalest show biz platitudes. Manager to Dreamgirl: "I'm going to make you the most famous woman who ever lived."

Deena (Sheryl Lee Ralph), the lead Dreamgirl, has larger ambitions. "I want to be more than an entertainer," she says. "I want to be an artist." Lorrell (Loretta Devine) is locked into a no-win affair with a married soul singer, who could pass for James Brown. But the evening's biggest tempest swirls around Effie (Jennifer Holliday), the rotund R&B performer, who is demoted from lead to backup singer and then, once success begins to rear its tantalizing head, is cavalierly bounced from the group altogether for a svelter Dreamgirl.

Effie will have the solace of a comeback on her own, but not before she rings down the first-act curtain with "And I'm Telling You I'm Not Going," an emotion-packed howl of frustration. Sitting at her dressing table in Las Vegas, she snarls her anger at having been dumped, pleads shamelessly to be kept on, and then builds to a stunning climax, as she spills out her love for the very manager who has engineered her dismissal. "You're the best man I've ever known," she wails, her voice tearing at the walls of the theater. Holliday turns herself inside out and the number is as galvanizing as any two others in "Dreamgirls."

But it is characteristic of the evening that Eyen has never really bothered to show us the deep love that Effie has been nurturing all this time in her ample breast. Holliday is required not only to reap the bitter consequences of the present in the song; she must fill us in on past happenings as well. That's a lot to ask of a performer. But "Dreamgirls" asks it time and again.

To director Bennett and his designers -- Robin Wagner (sets), Theoni V. Aldredge (costumes) and Tharon Musser (lights) -- has fallen the task of turning this piecemeal saga into a shining whole. And they very nearly do. Wagner has constructed four plexiglass towers, each encasing a battery of spotlights, and they glide furtively about the stage, defining and redefining the stark space. Then suddenly a shimmering curtain will waft down from above, almost like a beaded waterfall, or a modernistic staircase will light up, riser by riser. Rainbow colors come up out of the dark. The Dreamgirls, creatures of artifice and exotica, are about to make another fabled public appearance.

Unlike many musicals about show biz stars, though, "Dreamgirls" does convince you that this trio could have commanded the ovations, the adulation and even the overflowing press conferences that Eyen strews through his script. Aldredge's costumes play fur and sequin off naked flesh to further the impression that we are in the presence of profane goddesses. And composer Henry Krieger has written a medley of songs -- synchronized come-ons, really -- that neatly capture these performers' exhibitionistic drives. The title number, especially, is an insinuating bit of seduction.

The backstage scenes are not so persuasive, although Bennett's ability to weave performers and scenery together in a constantly shifting collage is almost cinematic in its effortless brilliance. There is next to no choreography on display. Perhaps to avoid any nefarious "Chorus Line" comparisons, Bennett has insisted that "Dreamgirls" is primarily a show about voices. But his choreographic instincts are at work in the smooth grace of the movable scenery, in the spotlight that closes in on a performer's face, then opens up seconds later to reveal that performer in a new situation entirely, or in the dramatic counterpoint of outrageously opulent costumes and vast futuristic horizons.

Holliday, with her direct, raw power, will no doubt emerge a star from the show. But the other performers are just as splendidly cast, above all Ben Harney as the man who masterminds the rise of the Dreamgirls and by his very rigor eventually assures their breakup. Even in stillness, Harney has cunning and energy to spare, and his eyes, while black as coal, seem to burn with opportunity.

Still, there's Eyen's clumsy book, and it presents serious obstacles to the evening's enjoyment. Bennett and company have done a lot. But even they can do nothing with a lyric like "You've got that air/They know a star is there." Or with drama that relies on such urgent pronouncements as "We open in Cleveland in a month."

DREAMGIRLS. Book and lyrics by Tom Eyen; music by Henry Krieger; directed by Michael Bennett; scenery, Robin Wagner; costumes, Theoni V. Aldredge; lighting, Tharon Musser; sound, Otts Munderloh; with Obba Babatunde, Cleavant Derricks, Loretta Devine, Ben Harney, Jennifer Holliday, Sheryl Lee Ralph.