But we’re not so lucky. Connor opens the door to the same room and stomps inside. He carries a candle, holding it aloft while he examines the spines of books on a shelf not far from where we hide.

Be ready, I warn Sebastian. We may have to move quickly if he gets too close.

Sebastian’s eyes are wide in the dim light. What do you think he’s searching for at this hour? He wrinkles his nose.

I shrug, but my curiosity has been piqued. I let my magic rummage around Connor’s brain, surprised at what I find.

It must be here. I need it to complete my research. Perhaps those foolish children took it back to their rooms. I can’t imagine what they might want with a book such as that, but if they did, there will be hell to pay.

As soon as Connor begins to move in a different direction, the pair of us sneak out of the room when his back is turned. I no longer suspect he might be the body walker, but I’m still not willing to take any chances. I have no doubt he’d use any excuse he could find to have us out from underfoot in the library. Soon we’re running down the hall, then up the stairs to the next level, and then the next, until finally we reach the floor with the map room.

Being sneaky is exhausting. And we haven’t even left the fortress yet.

The map room is usually kept locked, but Sebastian already took care of that problem. We snagged the master key from Rachel’s key ring before she locked us in our room, and then Sebastian made her forget before she could even object. The guilt Sebastian feels at deceiving her clings to him like a thick fog. But it was a necessary evil.

We unlock the door to the room holding all the ancient maps and artifacts and look around.

Where is the obsidian you saw? I ask, and Sebastian points to an alcove in a far corner. An array of artifacts crafted from the same pitch-black stone sits on a shelf behind a pane of glass. This time, the key doesn’t work—it must be only for doors—and we’re left with no choice. My heart sinks.

I don’t wish to deface any property in the library. The librarians have been kind and sheltered us. But we need protection from the body walker. Perhaps we can work off the debt of replacing the glass once we come back.

Ready? I ask Sebastian. Stand back.

I lob a heavy book at the glass. Much to my dismay, it only cracks, but the noise sends a shudder through us both. After a few tense moments, we relax. No one has come rushing down the hall outside, so we should be safe for now. I pick up another book, the heaviest I can manage to lift, and this time the glass shatters into tiny pieces on the floor. Thankfully, the artifacts aren’t affected, and Sebastian manages to grab a couple of them—two necklaces—without getting cut by the glass. He hands one to me, with a shiny, black orb I could get lost in if I stared at it too long, and puts the other, an arrowhead on an old chain, around his own neck.