Galadriel, or “El,” is a teenage wizard who was raised in a hippie commune by her mother, a magical healer. El is now in her junior year at a magical school called the Scholomance, where she keeps her famous mother a secret. El studies magical incantations, and specialty is death and destruction spells. She has no friends at the school or outside of it. There are no teachers or tutors at the Scholomance, but rather the students learn from the school itself through a unique form of independent study. The school is a large mechanical building set into a void outside of the normal world. Every year, the building rotates each residence hall down a layer, with students ending up on the bottom layer as seniors.
Life is dangerous for the wizards—especially student wizards. Magical creatures, known as maleficaria, constantly try to hunt down and eat them so that they can steal their magical energy, or mana. While the school does provide some shelter from the insatiable maleficaria, the mechanisms that cleanses the monsters from it are no longer fully functional. Students must be constantly on guard and never travel through the school alone, or a monster will likely devour them. Half the students are killed in this way before graduation—or during graduation, when the seniors must travel a long hall full of monsters to escape.
To cast spells, a wizard must have mana—which can be stored from physical exercise or taken from another source. Wizards who gain mana by stealing it from other living things are called maleficers. They are very dangerous and rarely tolerated. Many students mistakenly assume El—who has few friends and is quite gloomy—is a maleficer. El’s lack of popularity is dangerous for her because wizards require friendships and alliances to keep safe—both inside the Scholomance and in the outside world. While she is keenly aware that her powers would make her an extremely formidable maleficer if she chose that path, El rejects such an evil path to influence, in spite of the fact that her prospects for success on her own are extremely bleak.
The book begins with El, in her room at the Scholomance when a monster breaks in. It is immediately slain by Orion Lake—a fellow junior who is constantly saving other students from monsters. This irritates El, because she never asked to be saved and she would have welcomed the opportunity to show her powers and value to the other students. El also dislikes how other students constantly try to gain favor with Orion because of his tremendous abilities in fighting maleficaria and draining the valuable mana from them after killing them. But El’s biggest concern about Orion is that his having saved so many students from getting killed (which is the nature order of things at the Scholomance) has created a dangerous imbalance that threatens everyone.
Orion starts to follow El around, leading other students to assume that they are friends or even dating, which is highly unusual since they are at opposite ends of the social spectrum. Orion’s true motivation is in fact that he suspects El of being a maleficer and wants to keep a close eye on her. When a student who actually is a maleficer breaks into El’s room and attacks her, Orion saves her and then regrets having suspected her of dark magic. As Orion continues to spend time with El, he comes to values her company because she treats him like a person and not some valuable ally or weapon—in spite of the fact that El rarely misses an opportunity to be rude to Orion.
Many wizards live in exclusive enclaves that are separate from the real world, much like the school. The students at the Scholomance that are children of enclave wizards act very superior. These enclave kids have access to more resources and are constantly being helped by other students who hope to join an enclave after graduation. El’s social status at school rises (despite her misgivings about it) because she is spending so much time with Orion, who is a New York enclave kid. El manages to make some genuine friends as well as gain the interest of several of the enclaves, but much of the interest in El is motivated by the rival clans that are competing for Orion’s allegiance trying to influence Orion through her. El decides that she doesn’t want to be part of an enclave because the enclave structure only perpetuates the unfair cycle that wizards face.
An especially powerful kinds of monsters, a maw-mouth, breaches the the Scholomance’s defenses. The school itself intervenes by enticing El with a rare and valuable magical book in its library. El obtains the book and follows the monster, then she uses her awesome destructive power to kill the maw-mouth. But no one sees the event, so El’s reputation is not advanced by these heroics.
By saving so many students’ lives Orion has made walking down the graduation hall far more dangerous for the seniors, since now the hall will hold far more murderous maleficaria than it would have if Orion had let the students be killed. In response to this, four seniors try to let the monsters into the main part of the school to feast on the weaker students in the lower classes. After thwarting the seniors’ efforts, El, Orion, and their friends agree to a plan with the seniors that will help everyone. They will all team up to restore the broken mechanism that is supposed to purge the graduation hall of monsters. Although the plan is risky, all of the enclaves contribute mana to the group, so that they can cast powerful spells. They ultimately succeed fixing the cleansing machinery, and most of them return to the safety of the residence hall, although a few students are killed in the process.
Orion kisses El and she runs off. At the end of the book, El has won over most of the students that doubted her, and many of them respect her for her true potential as a wizard. She has several close friends as well. She talks to Orion, who is worried that she will leave him if he tries to date her. El tells him that she does not want to date him but will stay his friend. Everything seems to have worked out, but them El receives an unexpected message from her famous mother. The message is that her mother loves her and that her mother hopes El is keeping far away from Orion Lake.