Robin recommends Sorcery of Thorns by Margaret Rogerson

Step into a world of magical libraries and living books, with a plucky heroine and an intriguing mystery. Someone is attacking the Great Libraries of Austermeer, which throws Elizabeth into the courtly intrigue of the sorcerers. She soon discovers that things are not as she has been led to believe. To survive and unravel the mystery of who is attacking the libraries, she will have to team up with the enemy: a sorcerer and (gasp) a demon too. This book is one of those rare truly magical reads; engaging fantasy with adventure, mystery, and characters you can root for. The story is incredibly atmospheric, almost a gothic feel, and really draws the reader in. It would be an especially good read for the Fall and Halloween.
Publisher description:
When apprentice librarian Elisabeth is implicated in sabotage that released the library's most dangerous grimoire, she becomes entangled in a centuries-old conspiracy that could mean the end of everything.