Assassin of Truths by Brenda Drake (Library Jumpers #3)
The gateways linking the great libraries of the world don’t require a library card, but they do harbor incredible dangers. And it’s not your normal bump-in-the-night kind. The threats Gia Kearns faces are the kind with sharp teeth and knifelike claws. The kind that include an evil wizard hell-bent on taking her down. Gia can end his devious plan, but only if she recovers seven keys hidden throughout the world’s most beautiful libraries. And then figures out exactly what to do with them. The last thing she needs is a distraction in the form of falling in love. But when an impossible evil is unleashed, love might be the only thing left to help Gia save the world.