Spoilers ahead for The Invisible Library.
It opens with a prologue where Kai is kidnapped. Cuts back to the night before to follow Irene, Librarian in Residence, and Kai at an auction where they get their book, despite an annoyance in that someone tries to poison her, and are set upon on the way out. They learn some things from the thugs. Kai gets an invitation and is despondent to know his family knows he's here (to send it). Lord Silver actually tries to help with a warning.
And then we see Kai's disappearance from the point of view of Irene and Vale.
Their work to find him leads on to the rest of the tale. It reveals a lot more about the fae. It involves a city with many masks, Irene's speaking Arabic, a ghastly dungeon, Kai's uncle, a magical train, an opera house, another auction, and more.