It seems there was a power-struggle between two sets of then-existing nations (they were something like Projects, only horizontal instead of vertical) and both sets were equipped with atomic weapons. The Treaty of Oslo began by stating that atomic war was unthinkable, and added that just in case anyone happened to think of it only _tactical_ atomic weapons could be used. No _strategic_ atomic weapons. (A tactical weapon is something you use on the soldiers, and a strategic weapons is something you use on the folks at home.) Oddly enough, when somebody did think of the war, both sides adhered to the Treaty of Oslo, which meant that no Projects were bombed. Of course, they made up for this as best they could by using tactical atomic weapons all over the place. After the war almost the whole world was quite dangerously radioactive. Except for the Projects. Or at least those of them which had in time installed the force screens which had been invented on the very eve of battle, and which deflected radioactive particles. However, what with all of the _other_ treaties which were broken during the Ungentlemanly Gentleman's War, by the time it was finished nobody was quite sure any more who was on whose side. That project over there on the horizon might be an ally. And then again it might not. Since they weren't sure either, it was risky to expose yourself in order to ask. And so life went on, with little to remind us of the dangers lurking Outside. The basic policy of Eternal Vigilance and Instant Preparedness was left to the Army. The rest of us simply lived our lives and let it go at that. * * * * * But now there was a spy in the elevator. When I thought of how deeply he had penetrated our defenses, and of how many others there might be, still penetrating, I shuddered. The walls were our safeguards only so long as all potential enemies were on the other side of them. I sat shaken, digesting this news, until suddenly I remembered Linda. I leaped to my feet, reading from my watch that it was now ten-fifteen. I dashed once more from the apartment and down the hall to the elevator, praying that the spy had been captured by now and that Linda would agree with me that a spy in the elevator was good and sufficient reason for me to be late. He was still there. At least, the elevator was still out. I sagged against the wall, thinking dismal thoughts. Then I noticed the door to the right of the elevator. Through that door was the stairway. I hadn't paid any attention to it before. No one ever uses the stairs except adventurous young boys playing cops and robbers, running up and down from landing to landing. I myself hadn't set foot on a flight of stairs since I was twelve years old. Actually, the whole idea of stairs was ridiculous. We had elevators, didn't we? Usually, I mean, when they didn't contain spies. So what was the use of stairs?