Darnell Martin’s dramatisation of the rise of Chess Records and its recording artists affirms the image of the music industry as a beast that chews up its best talent, sucks out their creativity and spits them out when they are no longer of any use.

Only the strongest survive, frequently at the expense of weaker friends and rivals, and the price of fame can be extortionate: marriages torn apart by adultery, plagiarism and alcohol and drug addiction.

Fittingly for a film which sings the blues, Cadillac Records is a rather downbeat nostalgia trip full of woe, jealousy and betrayal, set in Chicago of the ‘50s and ‘60s.

Writer-director Martin evokes the era with the changing hairstyles, fashions and furnishings but his script is unfocused, cluttered with too many characters all clamouring for our limited attention.

Narrated by an aging Big Willie Dixon (Cedric The Entertainer), Cadillac Records steps back in time to the ‘40s to introduce the principal characters: guitar man Muddy Waters (Jeffrey Wright), who abandons the fields of Mississippi to chase his dreams of stardom, and Polish emigre Leonard Chess (Adrien Brody), who opens a bar on the south side of Chicago, where he can play music by the upcoming blues combos.

The first performers to catch his eye are Muddy and harmonica player Little Walter (Columbus Short), and Leonard spies an opportunity to cash in on the burgeoning record business.

Laying his family’s future on the line, he creates his own label - Chess Records - and makes Muddy his first signing.

Big Willie, Howlin’ Wolf (Eamonn Walker) and Chuck Berry (Mos Def) add to the expanding Chess Records clan.

When emotionally damaged Etta James (Beyonce Knowles) also signs, she threatens to destroy Leonard’s marriage as Chess Records and its stars burn too brightly.

Cadillac Records is the story of larger than life characters, who sang the blues, and lived them, ravaged by their various addictions or insecurities.

Most of the cast sing their alter ego’s tracks including "I’m Your Hoochie Coochie Man", "No particular Place To Go" and "Nadine".

Brody and Wright get lost amidst all of the musical performances and art direction, and Short makes his mark as the young upstart who boldly makes a play for his mentor’s wife.

"I’m Muddy’s woman," replies Geneva sternly.

"He got a lot of women. He can spare one," grins Little Walter, underestimating the strength of her loyalty.

The star turn here is Knowles, also one of the film’s producers, who is mesmerising as self-destructive songbird Etta James.

Her voice soars during a rendition of the classic "At Last" and when tears start welling in her eyes during a recording of "I’d Rather Go Blind", we feel every word pluck our heartstrings.

She is magnificent. Martin’s film, alas, is mediocre.