It's Valentine's Day, and everyone in Lisa's class receives cards except Ralph. Feeling bad for Ralph, Lisa quickly signs a card and gives it to Ralph. Ralph is instantly smitten with her. After school, he walks Lisa home, but Lisa has no feelings for Ralph, except pity. She tries to avoid him at school, but they are chosen to perform a play together.

Lisa is exasperated with Ralph, but when he asks her to go to Krusty's anniversary show with him, she is conflicted. She really wants to go but does not want to give Ralph the impression that she likes him. Homer advises her to go and enjoy the show. Arriving at the theatre, Lisa is paranoid about beeing seen with Ralph. During the taping, Krusty interviews members of the audience. When Ralph is questioned, he introduces Lisa as his date. Horrified, Lisa blurts out that the only reason she gave Ralph a Valentine card was because she felt sorry for him. Ralph's heart breaks.

Lisa realizes that she embarrassed Ralph in front of everyone. She wants to apologize, but does not get the chance before the night of the school play. Ralph transfers his grief into a good performance and mesmerizes the audience. After the play, young girls throw themselves at him. Later, Lisa gives Ralph another card, this time it is one that asks him to be her friend.