When it comes to "Cadillac Records," the music is great, but the movie's not. A biopic about the rise and subsequent fall of the Chicago-based, R&B/blues/jazz/rock-and-roll music label Chess Records, writer-director Darnell Martin takes such amazing liberties with the truth that it might as well be pure fiction that just so happens to involve real-life musicians. That Chess Records was run by brothers Leonard and Phil Chess, and in the film Leonard never even mentions having a sibling, let alone owning the company with one, gives you a pretty good idea of how accurate this puff piece is.

In 1941, Leonard Chess (Adrien Brody) is living in a lumber yard and telling the disgruntled father of his girlfriend, "Don't worry where I'm from, my wife's gonna drive a Cadillac." That poor gal is never seen or heard from again, and the next thing you know, he's opening up a club and, in 1950, a recording studio. Meanwhile, plantation worker Muddy Waters (Jeffrey Wright) is startled when he hears his own bluesy singing voice and moves to Chicago looking for a new life. He is the first aspiring musician Leonard hires, and before long they have the number-one song in the country with "I Can't Be Satisfied." As the years fly back, Chess goes on to make names out of Little Walter (Columbus Short), Chuck Berry (Mos Def), Howlin' Wolf (Eammon Walker), and Etta James (Beyoncé Knowles). By 1967, Chess Records closed down due to money woes and, as the film falsely claims, Leonard died from a heart attack before he was even able to drive out of sight of the studio.

Five minutes of online research following the screening of "Cadillac Records" confirmed my suspicions that the movie is a revisionist take on history. But what does this serve? Taken as pure fantasy, the movie keeps the viewer's attention by way of the fantastic soundtrack of golden oldies, but is a spotty dramatic mess that never finds a focal point. The narrative hops around from character to character and plot point to plot point like a child with hyperactive disorder. Writer-director Darnell Martin's view of the music industry in the 1950s and '60s is supremely naive, making it look like a bum could walk off the street and be a star within the week. Leonard Chess' business is skirted over with little detail, while story developments are brought up and dropped as fast as they arrive. The timeline spans roughly twenty-eight years, but only a couple of the characters appear to age more than a day.

That, then, leaves the music itself and a handful of fine performances to sporadically save the day. Adrien Brody (2007's "The Darjeeling Limited"), as Leonard, and Jeffrey Wright (2008's "W."), as Muddy Waters, are as close as the film gets to lead characters, but the former stands at a distance from the viewer, rarely making an impression, while the latter is portrayed as an unfaithful lout who isn't exactly the most likable of souls. On the other hand, Columbus Short (2007's "This Christmas") is a revelation as the spirited Little Walter, who slips into drugs and alcohol and is unable to return from the abyss of his addictions. As the tough yet troubled Etta James, Beyoncé Knowles (2006's "Dreamgirls") is also a standout, running away with all her scenes and showing giant strides in her climb toward becoming a legitimate actress. Knowles' onscreen performances of songs "At Last," "All I Could Do Is Cry," and "Once in a Lifetime" are such heart-rending powerhouses that, in the moment, the viewer is almost willing to forgive the film for being so uneven. Almost.

Alas, terrific tunes can only carry a motion picture so far, and the material in between them is scattershot at best. Creative liberties are expected when a movie is based on a true story, but "Cadillac Records" suggests that there was no respect and nary a moment of research involved when writer-director Darnell Martin decided to take on this project. She could make for a wonderful concert videographer, but even simple shot-to-shot continuity eludes her as a filmmaker. Tinges of natural magic squeak through the cracks, but, as a whole, "Cadillac Records" just doesn't take its premise seriously enough.