Lisa's feeling blue, but none of her family seems to understand. She hears distant saxophone playing, and sneaks off to investigate. She meets Bleeding Gums Murphy, a fellow jazz musician, who jams with her. Meanwhile, Homer and Bart play video boxing, where Homer is constantly being beaten. While Homer has nightmares about video boxing, Marge worries about Lisa.
The next day, Marge tells Lisa to smile, even though she is sad, to make her more popular. However, Marge sees Lisa's classmates take advantage of her, and tells her to be herself. Lisa becomes happy again.
Meanwhile, Homer takes lessons on video boxing from a kid at the arcade. Just as Homer is about to beat Bart back at home, Marge unplugs the TV to announce that the family are going out that evening. Bart decides to retire undefeated from video boxing.
That evening, the family go to The Jazz Hole, where Bleeding Gums Murphy plays.