Die Unsichtbare Bibliothek by Genevieve Cogman

In a world where alternate realities exist, a skilled librarian named Irene is tasked with retrieving valuable books from different dimensions to maintain the balance of order and chaos. Accompanied by her enigmatic assistant, Kai, she embarks on a mission to a steampunk-inspired London to recover a dangerous tome. As they navigate a city filled with supernatural creatures, secret societies, and unpredictable magic, Irene must use her wits and resourcefulness to outmaneuver adversaries and protect the secrets of the Library, all while uncovering hidden truths about her own past and the mysterious organization she serves.