Sorcery of Thorns Book by Margaret Rogerson

Then an act of sabotage releases the library’s most dangerous grimoire. Elisabeth’s desperate intervention implicates her in the crime, and she is torn from her home to face justice in the capital. With no one to turn to but her sworn enemy, the sorcerer Nathaniel Thorn, and his mysterious demonic servant, she finds herself entangled in a centuries-old conspiracy. Not only could the Great Libraries go up in flames, but the world along with them.

As her alliance with Nathaniel grows stronger, Elisabeth starts to question everything she’s been taught—about sorcerers, about the libraries she loves, even about herself. For Elisabeth has a power she has never guessed, and a future she could never have imagined.