Ofronia Mills is far too old to retire. She has spent her life as a librarian, and when Grand-Director Lorn Van Shipplestorm threatens not only her job, but the integrity of the library itself, she has no choice but to act. Evading her boss and Tess Dingly, it-girl and reluctant librarian apprentice, Ofronia descends into the library's forgotten fourth basement, which once housed the collection of magic books. While Van Shipplestorm plots to bar the general populace from entering the hallowed halls, Ofronia must decide what to do with what she finds. Will she entrust her fate to the magic she once refused to learn about? Or will she walk away quietly, like she has her entire life?