Mickey and the gang are putting on a concert of the St. Louis Blues. The show starts with a piano solo by Mickey. Minnie later appears on stage to sing the lyrics while Mickey continues to play the melody. When she is finished singing, she and Mickey begin scatting and dancing to the music. As the two leave the stage, the curtain rises to reveal a full band conducted by Mickey. As the piece progresses, Mickey steps into the spotlight again for a clarinet solo before conducting the big finale that literally brings the house down.
The song performed throughout Blue Rhythm, the St. Louis Blues, was written by composer W. C. Handy and was one of the earliest jazz pieces to become a part of popular music.
Pluto makes an odd out-of-character appearance in this short as a glove-wearing anthropomorphic trombone player. Interestingly enough, this predicted the Mickey Mouse Works cartoon "Pluto's Magic Paws", where Pluto gets a hold of a pair of magical gloves.
Mickey's "pie eyes" are back to being black ovals.