One of the great labels in music history, Chess Records was the empire of Leonard and Phil Chess, Polish brothers in Chicago who brought the likes of Muddy Waters, Little Richard, Etta James, Howlin' Wolf and Little Walter to the world. Chess Records altered the course of popular music, breaking down racial and social barriers and influencing thousands of artists in the process. That its story has taken so long to come to the screen is almost as astonishing as its music.

We first meet Leonard Chess (Brody) as a down-on-his-luck wheeler-dealer, selling records out of the back of his car and trying to scrape together enough money to open his own club. When he gets his name on a lease and starts booking bands he meets singer-guitarist Muddy Waters (Wright) and harmonica player Little Walter (Short) and, after gunshots are fired at a rival band on Chess' stage, he begins to work with them. Later Chess opens his own studio, using the money he's made from Muddy and Walter's records, and soon the icons-to-be start gravitating in his direction - Howlin' Wolf (Walker), Etta James (Knowles) and Little Richard (Mos Def) among them.

Having directed episodes of 'Grey's Anatomy', 'Law & Order' and 'ER', Darnell Martin works off her own script to create a film which, while no classic, is always watchable and has some very memorable scenes and performances. 'Cadillac Records' didn't have queues around the corner when it opened in the US and its poor take at the box office is puzzling - far weaker films have done far better business.

Martin has assembled a great cast and they all impress in their portrayal of the real people of the Chess story. The biggest problem that 'Cadillac Records' has is that the story is so interesting it needed to be a three-hour film, not a 100-minute one. Any of the characters onscreen could've been a film in themselves and you're left wanting to see more of all of them. If ever a film should've been a HBO series it's this one - each episode focussing on a particular legend.

The person whose reputation will be most enhanced by their performance here is Knowles. Her portrayal of Etta James is her best acting work to date and her flying off the handle, falling around in drink and drug dazes and effing and blinding like someone from 'The Wire' is so convincing that the singer should really think about doing edgier material in the future. All this and she only arrives halfway through the film. With a bit more time and a few more songs to belt out, she could've been up for an Oscar.

There will be Chess aficionados who will be disappointed that the story has been trimmed (no sign of Phil Chess, Bo Diddley or others) for the big screen and dramatic licence taken, but even they will agree that whatever the failings here, Martin has succeeded at the most important job of all: turning the uninitiated on to some of the greatest music on the planet.

Harry Guerin