This one was so good. Estranged half-sisters Joanna and Esther haven’t seen each other in ten years, but when their father is killed by one of the magical books he’s devoted his life to protecting, they must reunite to uncover an underworld of magical books and somewhat sinister librarians. The magic system in this book was so unique and fun. I also loved the characters and the banter. And I loved the overlapping multiple viewpoints (this is, I’m realizing, a theme for me).