The Burning Page (The Invisible Library #3) by Genevieve Cogman

The third title in Genevieve Cogman's clever and exciting The Invisible Library series, The Burning Page is an action-packed literary adventure!

Librarian spy Irene has professional standards to maintain. Standards that absolutely do not include making hasty, unplanned escapes through a burning besieged building. But when the gateway back to your headquarters dramatically malfunctions, one must improvise. And after fleeing a version of Revolutionary France astride a dragon (also known as her assistant, Kai), Irene soon discovers she's not the only one affected. Gates back to the Library are malfunctioning across a multitude of worlds, creating general havoc. She and Kai are tasked with a mission to St Petersburg's Winter Palace, to retrieve a book which will help restore order.