Irene has worked for years for the Library, a secret organization that collects works of fiction from all of the alternate worlds. The Library is enormous, but it’s in a place outside of all the worlds, outside of time. She gets regular assignments to enter various realities to procure particular books and bring them back to be housed in the Library. She takes on different identities and faces a fair share of danger, but to her the most important thing is just to have the opportunity to read good stories.

When Irene gets a new assignment to bring an important book back from an alternate London, she is paired up with a young man named Kai who’s new to the Library and needs mentoring on his first outing. She’s disturbed and confused to find out that they are being sent to an especially dangerous world where Library operatives would not normally go. And soon after they arrive, it becomes even more clear that this mission is far from typical: The book they plan to steal as quickly as possible and bring back to the Library has already been stolen. And plenty of other people in that London want the book, including a powerful faerie. Irene and Kai have to figure out where the book is and how to smuggle it out without being stopped by any number of very dangerous foes. On top of it all, Irene suspects Kai is hiding something.

The Invisible Library is a really fun book. If you’re a book lover, stories about secret libraries tend to be quite irresistible, for one thing. This book has magic of different kinds, adventure, mystery, and a little touch of potential romance. Irene and Kai end up getting help from a man who is much like Sherlock Holmes, and Irene thoroughly enjoys getting to pair up with a clever person like one of her fictional heroes. That holds true for the reader: it’s entertaining watching this brilliant private detective wield his deductive skills in a world that’s full of monsters and magic. Irene is a fairly young Library operative, so she doesn’t have a lot of experience, making the challenges she faces particularly difficult, but she is sharp and determined and willing to think outside of the box. Kai is a great foil for her and it’s interesting finding out what his secrets are. I’ll look forward to seeing where the story goes in the next book (lucky for fans of the book, there are seven more books so far).

Rated: Moderate. Profanity includes fewer than 10 instances of moderate profanity, about 20 uses of mild language, and one instance of the name of Deity in vain. Sexual content is limited to one character asking another if they wanted to sleep together, with the second declining, and then the two having a few sentences back and forth about how they have had previous lovers. Violence is moderate, with regular peril and fighting, attacks by nasty creatures, deaths and serious injuries, a good amount of blood, and a magic-fueled villain who wears the skins of other people.