Seemingly meant as an African-American Moulin Rouge, this visual blast of a homage to classic Hollywood musicals settles in as an odd hybrid, neither fish nor fowl. Nor foul, either, though not great--and ultimately, more idle than wild.

The platinum-selling hip-hop/R&B duo OutKast--André 3000 and Big Boi, here credited by their natural names, André Benjamin and Antwan A. Patton--make the jump to a starring feature after occasional and very separate supporting roles, with their regular video director, Bryan Barber, making his long-form debut. Part backstage musical, in which numbers are performed onstage naturalistically, and part book musical, in which performers sing and dance spontaneously as reality stops for a minute, Idlewild is a deliberately anachronistic phantasmagoria where modern expressions and rap songs punctuate an otherwise art-directed-to-an-inch-of-its-life gangster story set in the fictitious Idlewild, Georgia, in 1935. Production notes refer to it as "Prohibition-era," and while nitpickers will note that the 21st Amendment, repealing Prohibition, was ratified in 1933, Georgia didn't turn back its anti-alcohol laws until two years later.

Historical accuracy, of course, has never been the province of movies, let alone musicals, though writer-director Barber and company give documentary detail to every everyday object from knickers to knockers (door knockers-why, what did you think we meant?). Yet Barber still lets his imagination roam wildly free, with talking whiskey flasks, a vocal chorus of cuckoo clocks, and a rap number with showgirls pulling dance moves that aren't no Charleston or Lindy Hop.

As in most musicals, the plot is beside the point-this one revolves around a small-town speakeasy with a million-buck interior that could grace any dance club in Manhattan. With owner Ace (Faizon Love) and bootleg-hooch supplier Spats (Ving Rhames) out of the picture, singer Rooster (Patton) takes over, under the thumb of psycho gangster Trumpy (Terrence Howard). Rooster's childhood friend, piano-player Percival (a somnambulant Benjamin), a dutiful son to his comfortable, right-side-of-the-tracks mortician dad (Ben Vereen), falls for a singer (Paula Patton, no relation to Antwan) who's not what she seems. You can work out the rest, including what inevitably happens sometime after an old woman (Cicely Tyson) gives Rooster a Bible that he slips into his breast pocket.

If only all that were one-tenth as inspired as the movie's dizzying, kinetic dance sequences--choreographed by the great Hinton Battle, who's only 49 but already seems like an éminence grise--or Barber's flights of fancy, as when a white carnation in a black-and-white shot slowly bleeds itself red as the movie slips into color. There's visual bravura in every inventive angle and wipe, and in the canny way Barber plays on old-movie conventions that the OutKast audience probably wouldn't recognize. (Makes no difference if you're black or white-we're talking 14- to 25-year-olds, who don't generally tune in to TCM.) But the movie's slack narrative, predictability and often wayyyy-languid scenes make the movie seem far longer than its relatively modest length. The multiple, endless endings don't help.