Starring Jennifer Hudson, Jamie Foxx, and Beyoncé Knowles. Rated PG.

The first third of Dreamgirls is quite absorbing, both as an ersatz pop-culture artifact and as a vehicle for newcomer Jennifer Hudson. By the time the deep-voiced singer belts her way through the showstopping “And I Am Telling You I Am Not Going”, however, I began to wish I had sung that particular number at assignment time.

Hudson, a finalist famously rejected on American Idol, is a genuine discovery. The movie depends on the gravity of her voice and her physical presence to sell some pretty thin stuff—something that works well until the fraudulent nature of the story makes the 130-minute film drag by ever more slowly.

It’s beyond ironic that the musical, a Broadway staple from the 1980s (created by Henry Krieger and Tom Eyen), attempts to make a statement about authenticity—specifically the dilution of black music in American entertainment—when the film version is so spectacularly superficial. Its central premise is that people don’t know, or actively fear, real soul when they see it. And that’s unintentionally borne out by this production.

To begin with, Jamie Foxx, so strong as Ray Charles in 2004’s Ray, seems stiffly uncomfortable as Curtis Taylor Jr., a Berry Gordy–like businessman who builds a small stable of Detroit R&amp?B acts into a crossover empire. Fortunately, key artist Jimmy “Thunder” Early is played by Eddie Murphy, who rolls elements of James Brown, Jackie Wilson, and Marvin Gaye into a compelling, if not always convincing, character. He represents the street cred Taylor is happy to trade in for mainstream success, which comes via the Dreams, a trio patterned after the Supremes. In this case, however, it’s with an oddly benign Diana Ross–type character who is blandly resigned to her boss’s Svengali-like manoeuvres.

The Ross figure, here called Deena Jones, is played by Beyoncé Knowles, who effortlessly holds the camera, preparing us for, well, nothing. With all her film experience in recent years, the Destiny’s Child lead singer still shows no sign of being able to act. When Taylor makes the prettier, thinner singer the Dreams’ lead instead of Hudson’s earthier Effie White, Knowles doesn’t even seem to notice. Later, after she replaces Effie in his bedroom too, Deena starts to wonder what makes her so special, and we have to concur.

Plot problems abound, and director Bill Condon’s strategy—to restrict songs to organic, theatrical settings for the first half-hour before having characters suddenly erupt into fully orchestrated crooning—will alienate as many viewers as it engages. (Condon wrote the screenplay for Chicago, by the way.) But the real problem here isn’t with the acting or the structure; it’s with the music. The songs themselves are pale imitations of the Motown and rawer Stax/Volt numbers they are meant to evoke. What’s next? Malcolm X, played by Pat Boone?