The first shots of Beyonce Knowles as singer Etta James from the upcoming "Cadillac Records" film have appeared online. The picture features Knowles singing the ballad "At Last." According to director Darnell Martin (Their Eyes Were Watching God): "People said, 'I would have worked for free today.'"

"Cadillac Records" revolves around Leonard Chess, the legendary founder of the South Side Chicago blues label Chess Records. The period piece follows the rise and fall of the record company, which launched the careers of such R&B greats as Muddy Waters, Etta James and Chuck Berry. Chess, who was inducted into the Rock and Roll Hall of Fame in 1987, scoured the South, checking out the various blues scenes and selling records from the back of his Cadillac.

Cedrick the Entertainer will play Willie Dixon, who wrote most of the hit records and was part of the famous company. Oscar winner Adrien Brody has will play Leonard Chess, the founder of Chess Records. Jeffrey Wright will portray Muddy Waters.