They got off on Emily’s floor and their ears popped. The air smelled just the least bit fried and stuffy here, fifty floors up. Arcane color-coded maps on the walls. They caught a hall bus. Crabbed little nooks and crannies branched off, leading into patios—what the sociologists called "defensible space." Emily led them off the bus and up a nook. A security mouse scuttled along the floor—nasty-looking little microbot with fretted eyes and a muzzle clotted with dirt. Emily carded the door open.