The northern pass in early morning smells like cold pine and wet rock and nothing else. I'd been out here twice before — once during initial fortress orientation, once during a perimeter expansion that turned out to be unnecessary. Both times it had felt like the edge of something, the place where the fortress's gravity stopped pulling, and the rest of the world started. Standing in it now with Evan on my left and Zane three paces ahead, I felt it again. That specific quality of exposure that open terrain gives you, the way it makes you aware of exactly how small a person is. "Movement pattern on the eastern ridge is twelve minutes," Evan whispered. He was reading from a small notebook; the handwriting was so small that I couldn't make it out from where I stood. "That's our window fo

