"Dreamgirls," the new adaptation of the 1981 Broadway musical hit, is so good that you want to take it and beat it over the head and shake it because of the one unforgivable failure that keeps it from being truly great. But first let me tell you the good news. The film is a libel-free version of the lives and careers of the Supremes - here they're called the Dreamettes, shortened to the Dreams - from their start at a Detroit amateur-night contest where the manager of soul singer James Thunder Early (Eddie Murphy, and you can read James Brown) hires them as backup singers. But Cadillac salesman Curtis Taylor Jr. (Jamie Foxx) gets to squeeze out both James and their manager, Marty Madison (Danny Glover) and, in another libel-free version, this time of Berry Gordy Jr.'s career as the maker of Motown, takes over their lives and careers.

I said I'd start with the good news, and it begins with Eddie Murphy and Jennifer Hudson, a loser on "American Idol" but a powerhouse singer and natural actress here. She is Effie White, the lead singer of the Dreamettes and the Dreams, until Curtis moves her to backup in favor of the prettier, slimmer Deena Jones (Beyoncé Knowles), whom he also chooses to replace Effie in his bed. (Diana Ross was also a backup until she was moved to replace the group's lead, who later died in poverty.) Hudson is so good she could make the Alphabet song into a show-stopper. And Murphy, who reportedly had to be talked into taking the role, has a ball here, singing, strutting and jiving on the stage, with his iridescent wardrobe and his James Brown pompadour.

The direction by Bill Condon, who also wrote the screenplay, is bold and elegant, moving without effort from intimate moments when a character sings a phrase or two about his or her feeling, then cutting to the continuation of the song as a performance on a stage with full production. Condon treats the music as an equal part of the film's structure, not pausing to set it apart, or place it only in a performance venue or other location, which would separate it from the spoken words. He made the script from the original book and lyrics by Tom Eyen and the music by Henry Krieger, which won numerous Tonys on Broadway. Condon would seem an odd choice for "Dreamgirls," since his two other films as director were "Gods and Monsters" and "Kinsey," but he was the screenwriter for the film of the musical "Chicago," and he obviously has a feel for the genre.

Now for the bad news: The script can't seem to decide whether to focus on the characters or the music, and it seems as though some important, revealing material about the people has been left out or cut away; we have little feeling for Curtis and his machinations until a sudden reversal of fortune near the end. Similarly, the three women should have been more richly drawn; Hudson manages to endow Effie with personality and feelings, but Deena is a passive cipher and their third, Lorell (Anika Noni Rose), is hardly present at all.

Even worse is the unfortunate fact that every one of the songs is pedestrian; neither the music nor the lyrics seem worth listening to, much less making a fuss over. Moreover, none of them even faintly reflect the genius of soul or rhythm & blues, which was the heart of the great Motown sound. We may have a lot to thank Stephen Sondheim for in the American musical theatre, but taking the beat away from popular music isn't one of them; "Dreamgirls" is a Motown movie without the Motown beat.