The hole was getting smaller.

As Jules had explained, wherever the Daban Urnud’s architects had needed to forge a connection between major parts of the Core, they had used a ball valve, which was just a sphere with a fat hole drilled through the middle, held captive in a spherical cavity bridging the two spaces in question. The sphere couldn’t go anywhere, but it was free to rotate. Depending on how the hole in its middle was aligned, it could allow free passage or form an impregnable barrier. Such a valve was set into the “floor” of this chamber. It was so huge that, at first, I hadn’t seen it for what it was. But now that it had gone into motion, its nature and its function were perfectly obvious. It moved ponderously, but by the time Fraa Jad managed to draw my attention to it, the thing was already about half closed, like an eyeball slowly drifting into sleep.

Fraa Jad planted his feet against a soldier’s backside and shoved off, driving the soldier toward the ceiling and Jad down toward the ball valve. I was already near a sort of ladder or catwalk, which I pushed off against to propel myself after him. When we got to the ball valve, the aperture had narrowed to perhaps three feet at its widest—plenty of room to squeeze through. But we had used up all of our momentum just getting there, and our aim had been miserable. After some feverish banging around we drifted through the aperture and found ourselves hovering in the bore of the sphere, watching the eye at its other end get smaller. There were no handholds that we could use to move ourselves along. If we didn’t reach the other end by the time it closed, we’d be imprisoned until the next time they opened the valve.

I was too out of breath to do much anyway. I aimed my fire extinguisher back the way we’d come and pulled the trigger. The recoil forced it back against me; I took the force with my arms and felt myself tumbling backwards. But I was moving. I slammed into the socket-wall at the end, scrabbled for a handhold on the rim of the hole, and pulled myself through. A second later Fraa Jad squirted through on a snowy plume of fire retardant. I grabbed his ankle, which slowed him down quite a bit. We found ourselves adrift and slowly tumbling at the forward extremity of the two-mile-long, hundred-foot-diameter shaft that ran the length of the Orbstack. We had made it to the Core. And if any of those we’d left behind in the bearing chamber had found our behavior suspicious, they had not been adroit enough to follow us through the ball valve. Smaller hatches—airlocks, made for one person at a time—were planted around it so that people could pass between Core and bearing chamber even when the ball valve was closed. I kept a nervous eye on those, half expecting a space cop to fly out and accost us, but then reasoned that it simply wasn’t going to happen. Jules’s words of a few minutes ago came back to me. What the Valers had done—what we had done—had been the worst military embarrassment these people had suffered in a thousand years. The bomb was still on fire, the disaster only getting started. The Valers might still be alive and fighting. So they weren’t going to make a big deal about a couple of firefighters acting weird.

Our panicky flight through the valve had imbued us with momentum that carried us outward toward the wall of the Core, which was rotating about as fast as the second hand on a clock. This meant that when we drifted into the wall, it was moving past us at a brisk walking pace. This part of the Core wall was covered with a grid with convenient hand-sized holes between the bars, so we did what came naturally and grabbed it. The effect was gentle but inexorable acceleration that made our feet spin out to find purchase on the grid. We were now rotating along with everything else. Here our body weight was less than that of a newborn infant. But it was the most “gravity” we had known for a long time, and took a little getting used to.

We clung to it for a couple of minutes, gasping for air, trying not to black out. Then Fraa Jad, never one to discuss his plans and intentions with his traveling companions, pushed off and glided along the Core wall, headed for the first of the four great Nexi that were spaced evenly along its length. Travel was easier in micro- than in zero gravity, because we slowly “fell” to the Core wall where we could always push off and get another dose of momentum. Available was a sort of rapid transit system, consisting of a moving conveyor-belt-cum-ladder that glided up one side of the Core and down the other. Most of the people we could see—perhaps a hundred, heavily skewed toward soldiers and firefighters—were using it. The rungs were elastic, so that when you grabbed one it didn’t simply jerk your arm from its socket. Tired as I was, I was tempted to have a go, but didn’t want to make a spectacle of myself. Fraa Jad showed no interest. We moved more slowly than those who were using it, which worked to our advantage: some of them shouted questions at us as they glided by, but none was inquisitive enough to jump off and pursue the conversation.

In a few minutes we came to the station in the Core where the forward-most Orbs—One, Five, Nine, and Thirteen—were connected. Each of these stood at the head of a stack of four. So, Orbs One through Four were for the Urnudans. Five through Eight were Troan, Nine through Twelve were Laterran, and the rest Fthosian. By convention, the lowest-number Orb in each stack—the ones that connected here, at the heads of the stacks—were for the highest-ranking members of their respective races. So this Nexus was the most convenient place for the Geometers’ VIPs to meet. From where we were, it didn’t look like much: just four cavernous holes in the wall, the termini of perpendicular shafts leading out to the Orbs. According to Jules, though, if we were to look at it from the outside, we would see that this part of the Core was wrapped in a doughnut of offices, meeting-chambers, and ring-corridors where the Command had its offices. Several hatches in the Core wall hinted at this. But conflict between Pedestal and Fulcrum had led to a division of the Command torus into parts of unequal size. Hatches had been locked, partitions welded into place, guards posted, cables severed.

None of which concerned us very much, since the space we were in served only as a service corridor or elevator shaft, rarely visited or thought about by the Command. Of much greater interest to us were the four huge orifices in the Core wall. As we drifted into the Nexus we were able to gaze into these and see tubular shafts, each about twenty feet in diameter, each leading “down” about a quarter of a mile. At the “bottom” of each was another huge ball valve, currently closed. Beyond each such valve was an inhabited Orb a mile wide.

It wasn’t difficult to identify the shaft leading to Orb One. A large numeral was painted on the Core wall next to it. The numeral was Urnudan, but any sentient being from any cosmos could recognize it as the glyph that represented unity, 1, a single copy of something. I, however, did not have time to linger and contemplate its profound meaning, as Fraa Jad had already located a ladder bracketed to the wall of the shaft, and begun to descend it.

I followed him. Gravity slowly came on as we went. It’s hard to describe how terrible this made me feel. The only thing that kept me from passing out was fear I’d let go of the rungs and fall down on top of Fraa Jad. During the worst spell, a voice drilled into my awareness and made my skull buzz. Fraa Jad had begun to sing some Thousander chant like the one that had kept me awake at the Bazian monastery on the night we had been Evoked. It gave my consciousness something to hold on to, like the steel ladder-rung that I was gripping with my hand: my only hard tangible link to the giant complex spinning around me. And in the same way that the rung kept me from falling, the sound of Jad’s voice in my skull kept my mind from floating away to wherever it had gone when I’d passed out in the observatory and awoken on the wrong worldtrack.