Leo sets the stage for us in the beginning by giving us some insight into his history. He tells us an anecdote, or short personal story, about how his uncle once had a porcupine tie that Leo falls in love with. He wants to start a collection, and it's clear right away that Leo doesn't always follow the latest fashion crazes. He has a mind of his own. Now in high school, Leo hears about a girl who has a mind of her own, too. She's new in school, and her name is Stargirl. She's quite quirky and very, very interesting, like, say, a porcupine tie?
People have a tough time accepting Stargirl at first. She's just so different. This doesn't hold Stargirl back, and even though it is not her intention, she becomes quite well liked and popular for a spell, and our narrator Leo is falling for her. But what should he do about a crush on someone who is so, well, strange?
The high school turns on Stargirl for her unique behavior, particularly when she shows compassion to a member of a rival basketball team. A school wide movement to shun Stargirl begins. But Leo is totally, madly, head over heels, in love with her. He's miserable without her, but he's miserable without the acceptance of his high school classmates, too. So he has to make a choice between being with Stargirl and being one of the crowd.
Stargirl proudly announces her love for Leo by painting a giant heart on a bed sheet with the words STARGIRL LOVES LEO in the middle of it, which she posts on the bulletin board at school. Leo loves her, too, but he's also totally embarrassed. When Stargirl asks him how he feels about the banner, a fight ensues, and Leo begins to avoid her. He tells her he doesn't want to break up, but that something has to change. And by something, he means Stargirl.
Will she change? Will she be accepted by society again? At first, it looks like the answer is yes. Stargirl disappears and Susan takes her place. Susan looks and acts just like all the other girls at school, and Leo gives her lessons on how to be even more normal. She gives it her best shot, but the students still won't let her in with the in crowd.
By this point, it's clear that Leo prefers the affections of the group to Stargirl's affection. Susan decides to stop trying to be popular and embraces her true self again. Stargirl is back in all her glory. She does not put on a big scene when she and Leo break up; she just tells him it's cool if he doesn't ask her to the ball. She goes to the ball stag, and dressed to the nines. She enjoys herself completely, and somehow, she regains her popularity that night, leading all the students in a rendition of the bunny hop. The only trouble is, the mean girl at school, Hillari, still hates Stargirl, and slaps her in front of the entire school. Can't Stargirl just catch a break?
No one from the school ever sees Stargirl again after that night at the ball. She and her family move out of town. Archie and Leo continue to talk about Stargirl from time to time, trying to figure out who she was and where she went. Leo has become a hard-working set designer who still thinks of Stargirl and hopes for another chance one day. Just last month, he received a porcupine necktie in the mail. Is there hope for the two to reunite in the future? Shmoop likes to think so.