It seemed to be a common occurrence in the 30s and 40s both in the USA and UK to construct films around non actor bandleaders.Sometimes you would actually involve them attempting to act eg Harry Roy in the UK or you would actually base a film on a band leaders life eg The Benny Goodman Story,or you would integrate a band leader in a fictional story ,as in this film.Clearly in the instance of this film,and given that Lewis appears only at the beginning and end his name is being used more for its celebrity value.The music is worth while listening to but the story is so familiar it could write itself.I would not bother to go out of my way to see this film again