Ding Dong Williams on AllMovie

A moody but extremely talented clarinet playing band-leader is contracted to write a symphonic, bluesy soundtrack for an upcoming film. Unfortunately, he can neither read nor write music. Instead he simply plays whatever he feels. The comedy in this musical begins when two professional arrangers are hired to transcribe his playing. Unfortunately, every time the musician's mood changes so does his style, so they must figure out some way to get him in a blue mood and keep him there till the project is completed.