A string of graffiti tags have been appearing around Springfield, and the trail points to... Lisa?!
As Springfield's citizens spot distinctive graffiti popping up around the city, Lisa Simpson is busy working on her beautiful painted portrait of Springfield Elementarty in hopes of getting some respect in the upcoming Art Show. On the day of the Art Show, Lisa finds that nobody is noticing her painting and leaves out of boredom.
When she returns, Lisa finds the judge Professor Lombardo fawning over her painting and awards it First Prize: $50. However, she is horrified to see that it has been tagged with graffiti, and everybody starts blaming her for the other tags through town. Bart suddenly butts in to admit that it was his tag and that he deserves first prize. Groundskeeper Willie then arrives to announce that Bart had just tagged the front of the school and signed it. Bart tries to argue that he didn't do it, but his protest falls on deaf ears as everybody chases him out of the school.
Lisa sighs at being unnoticed once more, and Willie cheers her up by reminding her that she has the prize money and Bart got his comeuppance. However, even Lisa doubts that Bart could have tagged the school, but Willie tells her not to think of it as he walks away... with a spray can in his back pocket.