Aurelia "Aurie" Silverthorne and her younger sister, Pi, are the two strongest mages to apply to the Hundred Halls in decades. But their parents' death when they were kids leaves them without an easy path to join the magical university. Each Hall-the schools in charge of teaching specific kinds of magic-have expectations for entry. Pi wants to join Coterie of Mages, the most exclusive Hall at the school, but it requires sponsorship by an alumnus...