Dreamgirls is the rare movie musical with real rapture in it. The opening cowbell clank could be a metronome to set your pulse to, and moments later, as we're plunked into amateur night at a Detroit theater in the pomade-and-sequin early '60s, where a group of funky chorines with gyrating booties are singing ''I'm Lookin' for Something,'' the effect is so ecstatic it just about lifts us off the ground. The jumpin'-jive editing isn't just music-video clutter; it works in beautiful smooth tandem with the whooshing, darting camera. The director, Bill Condon (Kinsey), adapting the famously glittering Broadway musical that was first staged in 1981, hooks us into a mood of swirling, infectious freedom, and he doesn't let go. Dreamgirls, a candy-striped roman à clef, is, of course, a thinly veiled version of the rise of the Supremes and Berry Gordy's Motown. The slightly sinful jaunt of the music is the sound of a revolutionary new optimism of a desire to break out and rise up, to set the world on fire with joy.
As a girl-group trio called the Dreamettes takes the stage, their lead vocalist, saucy, plush-figured Effie (Jennifer Hudson), sings the way that a lion roars, blasting the roof off with her full-throated gospel vibrations. She's as churchy and volcanic as the young Aretha Franklin, and as cleansing, too. Backstage, Curtis Taylor Jr. (Jamie Foxx), a snake-eyed hustler of astonishingly nimble charm, sweet-talks the group into letting him be their manager. He sets them up as backup singers for James ''Thunder'' Early (Eddie Murphy), a fading, salacious funk-blues belter who instantly teaches them a song, line by line, as the camera rotates into a concert performance; it's a thrilling, starstruck moment. Murphy, a-sizzle, plays this raspy James Brown showman by drawing on his lickety-split timing, but he also makes Early just a bit too quick on the draw, as if he were racing from the knowledge that his time was passing.
Stymied by the music industry's racism, Curtis pays off radio stations, a necessary evil captured in the furious, low-down ''Steppin' to the Bad Side.'' Then he spins the Dreamettes into a group of their own, which is when he makes his real deal with the devil: Though Effie is his paramour, he replaces her, as lead singer and in the bedroom, with the svelte, doll-featured, light-skinned backup singer Deena Jones (Beyoncé Knowles). It's not just a cosmetic change. As Curtis tells Effie, her voice is too ''special'' that is, too black. The resonance of the movie is the way it makes us see that Curtis, in his attempt to take on an industry that rips off black artists yet denies them access to the pop charts, has to replace Effie. He's a scoundrel, but he makes the leap to a new sound, a new era, of elegant girl-group pop only by consigning his purest vocal talent to the trash heap.
Condon has staged Dreamgirls, or at least the electrifying first hour of it, as a single, flowing eruption of storytelling energy. As the Dreamettes become Deena Jones and the Dreams, the film's liquid jukebox-operetta style expresses the American crossover fantasy: the hunger to flood as vast an audience as possible with pure feeling. Yet even as the characters express themselves, thrillingly, through song, their personal entanglements love affairs, descents into poverty and drug addiction remain a tad abstract. In Dreamgirls, we're watching a tale of the evolution of black pop music in which black pop music is, in essence, the protagonist. When Effie, tossed out of the trio before a nightclub show, does her big number, ''And I Am Telling You I'm Not Going,'' she's singing it to the two-timing Curtis, but it's really about the Dreams, with the gospel screamer going over the top into loss and desire, bidding goodbye to the musical fusion that no longer needs her.
Hudson's performance of this song is an epiphany, as grandly shattering a piece of musical acting as the movies have seen since Judy Garland wailed about ''The Man That Got Away'' in 1954's A Star Is Born. Yet having charted the triumph, and compromise, of black pop, Dreamgirls, in its second half, turns to the tale of what happens to all of these people and since they're archetypes more than individuals, the drama is a bit hollow. It needed to be juicier, pulpier, more madly melodramatic. Curtis, high on success, becomes as controlling as the white power brokers he despised he loses his soul to become the Man yet why is Beyoncé's Deena such a saint? It's not as if Diana Ross, say, lacked a sense of power. The film's one true diva, Effie, falls into poverty and despair, but her saga never quite tears our hearts up. Dreamgirls begins as a star-spangled dream of a musical, yet it ends up earthbound enough to be a very good movie rather than a great one.