At just before 5:00 p.m. on a weekday, the upper track level of Grand Central Terminal looks much as it does at any other time of day: a striped gray landscape of long concrete islands stretching away from you into a dry, iron-smelling night, under the relentless fluorescent glow of the long lines of overhead lighting. Much of the view across the landscape will be occluded by the nine Metro-North trains whose business it is to be there at that time, and by the rush and flow of commuters through the many doors leading from the echoing Main Concourse to the twelve accessible platforms’ near ends. The commuters’ thousands of voices on the platforms and out in the Concourse mingle into a restless undecipherable roar, above which the amplified voice of the station announcer desperately attempts to rise, reciting the cyclic poetry of the hour: ” … now boarding, the five oh two departure of Metro-North train number nine five three, stopping at One Hundred and Twenty-Fifth Street, Scarsdale, Hartsdale, White Plains, North White Plains, Valhalla, Hawthorne, Pleasantville, Giappaqua …” And over it all, effortlessly drowning everything out, comes the massive basso B-flat bong of the Accurist clock, echoing out there under the blue-painted backwards heaven, two hundred feet above the terrazzo floor.

Down on the tracks, even that huge note falls somewhat muted, having as it does to fight with the more immediate roar and thunder of the electric diesel locomotives, clearing their throats and getting ready to go. By now Rhiow knew them all better than any trainspotter, knew every engine by name and voice and (in a few specialized cases) by temperament … for she saw them every day in the line of work. Right now they were all behaving themselves, which was just as well: she had other work in hand. It was no work that any of the other users of the Terminal would have noticed—not that the rushing commuters would in any case have paid much attention to a small black cat, a patchy-black-and-white one, and a big gray tabby sitting down in the relative dimness at the near end of Adams Platform … even if the cats hadn’t been invisible.