Hirz turned to look at Childe. Small as she was, she looked easily capable of inflicting injury. “Start talking, dickhead.”

  Childe spoke with quiet calm. “I put modifiers in your brain, via the wrist shunt. The modifiers haven’t performed any radical neural restructuring, but they are suppressing and enhancing certain regions of brain function. The effect—crudely speaking—is to enhance your spatial abilities, at the expense of some less essential functions. What you are getting is a glimpse into the cognitive realms that Celestine inhabits as a matter of routine.” Celestine opened her mouth to speak, but he cut her off with a raised palm. “No more than a glimpse, no, but I think you’ll agree that—given the kinds of challenges the Spire likes to throw at us—the modifiers will give us an edge that we lacked previously.”

  “You mean you’ve turned us all into maths geniuses, overnight?”

  “Broadly speaking, yes.”

  “Well, that’ll come in handy,” Hirz said.

  “It will?”

  “Yeah. When you try and fit the pieces of your dick back together.”

  She lunged for him.

  “Hirz, I . . .”

  “Stop,” I said, interceding. “Childe was wrong to do this without our consent, but—given the situation we find ourselves in—the idea makes sense.”

  “Whose side are you on?” Hirz said, backing away with a look of righteous fury in her eyes.

  “Nobody’s,” I said. “I just want to do whatever it takes to beat the Spire.”

  Hirz glared at Childe. “All right. This time. But you try another stunt like that, and . . .”

  But even then it was obvious that Hirz had come to the conclusion that I had already arrived at myself: that, given what the Spire was likely to test us with, it was better to accept these machines than ask for them to be flushed out of our systems.

  There was just one troubling thought which I could not quite dismiss.

  Would I have welcomed the machines so willingly before they had invaded my head, or were they partly influencing my decision?

  I had no idea.

  But I decided to worry about that later.

  FIVE

  “Three hours,” Childe said triumphantly. “Took us nineteen to reach this point on our last trip through. That has to mean something, doesn’t it?”

  “Yeah,” Hirz said snidely. “It means it’s a piece of piss when you know the answers.”

  We were standing by the door where Celestine had made her mistake the last time. She had just pressed the correct topological symbol and the door had opened to admit us to the chamber beyond, one we had not so far stepped into. From now on we would be facing fresh challenges again, rather than passing through those we had already faced. The Spire, it appeared, was more interested in probing the limits of our understanding than getting us simply to solve permutations of the same basic challenge.

  It wanted to break us, not stress us.

  More and more I was thinking of it as a sentient thing: inquisitive and patient and—when the mood took it—immensely capable of cruelty.

  “What’s in there?” Forqueray said.

  Hirz had gone ahead into the unexplored room.

  “Well, fuck me if it isn’t another puzzle.”

  “Describe it, would you?”

  “Weird shape shit, I think.” She was quiet for a few seconds. “Yeah. Shapes in four dimensions again. Celestine—you wanna take a look at this? I think it’s right up your street.”

  “Any idea what the nature of the task is?” Celestine asked.

  “Fuck, I don’t know. Something to do with stretching, I think . . .”

  “Topological deformations,” Celestine murmured before joining Hirz in the chamber.

  For a minute or so the two of them conferred, studying the marked doorframe like a pair of discerning art critics.

  On the last run through, Hirz and Celestine had shared almost no common ground: it was unnerving to see how much Hirz now grasped. The machines Childe had pumped into our skulls had improved the mathematical skills of all of us—with the possible exception of Trintignant, who I suspected had not received the therapy—but the effects had differed in nuance, degree and stability. My mathematical brilliance came in feverish, unpredictable waves, like inspiration to a laudanum-addicted poet. Forqueray had gained an astonishing fluency in arithmetic, able to count huge numbers of things simply by looking at them for a moment.

  But Hirz’s change had been the most dramatic of all, something even Childe was taken aback by. On the second pass through the Spire she had been intuiting the answers to many of the problems at a glance, and I was certain that she was not always remembering what the correct answer had been. Now, as we encountered the tasks that had challenged even Celestine, Hirz was still able to perceive the essence of a problem, even if it was beyond her to articulate the details in the formal language of mathematics.

  And if she could not yet see her way to selecting the correct answer, she could at least see the one or two answers that were clearly wrong.

  “Hirz is right,” Celestine said eventually. “It’s about topological deformations, stretching operations on solid shapes.”

  Once again we were seeing the projected shadows of four-dimensional lattices. On the right side of the door, however, the shadows were of the same objects after they had been stretched and squeezed and generally distorted. The problem was to identify the shadow that could only be formed with a shearing, in addition to the other operations.

  It took an hour, but eventually Celestine felt certain that she had selected the right answer. Hirz and I attempted to follow her arguments, but the best we could do was agree that two of the other answers would have been wrong. That, at least, was an improvement on anything we would have been capable of before the medichine infusions, but it was only moderately comforting.

  Nonetheless, Celestine had selected the right answer. We moved into the next chamber.

  “This is as far as we can go with these suits,” Childe said, indicating the door that lay ahead of us. “It’ll be a squeeze, even with the lighter suits—except for Hirz, of course.”

  “What’s the air like in here?” I asked.

  “We could breathe it,” Forqueray said. “And we’ll have to, briefly. But I don’t recommend that we do that for any length of time—at least not until we’re forced into it.”

  “Forced?” Celestine said. “You think the doors are going to keep getting smaller?”

  “I don’t know. But doesn’t it feel as if this place is forcing us to expose ourselves to it, to make ourselves maximally vulnerable? I don’t think it’s done with us just yet.” He paused, his suit beginning to remove itself. “But that doesn’t mean we have to humour it.”

  I understood his reluctance. The Spire had hurt him, not us.

  Beneath the Ultra suits which had brought us this far we had donned as much of the lightweight versions as was possible. They were skintight suits of reasonably modern design, but they were museum pieces compared to the Ultra equipment. The helmets and much of the breathing gear had been impossible to put on, so we had carried the extra parts strapped to our backs. Despite my fears, the Spire had not objected to this, but I remained acutely aware that we did not yet know all the rules under which we played.

  It only took three or four minutes to get out of the bulky suits and into the new ones; most of this time was taken up running status checks. For a minute or so, with the exception of Hirz, we had all breathed Spire air.

  It was astringent, blood-hot, humid, and smelt faintly of machine oil.

  It was a relief when the helmets flooded with the cold, tasteless air of the suits’ backpack recyclers.

  “Hey.” Hirz, the only one still wearing her original suit, knelt down and touched the floor. “Check this out.”

  I followed her, pressing the flimsy fabric of my glove against the surface.

  The structure’s vibrations rose and fell with increased strength, as if we had excited it by
removing our hard protective shells.

  “It’s like the fucking thing’s getting a hard-on,” Hirz said.

  “Let’s push on,” Childe said. “We’re still armoured—just not as effectively as before—but if we keep being smart, it won’t matter.”

  “Yeah. But it’s the being smart part that worries me. No one smart would come within pissing distance of this fucking place.”

  “What does that make you, Hirz?” Celestine asked.

  “Greedier than you’ll ever know,” she said.

  Nonetheless we made good progress for another eleven rooms. Now and then a stained-glass window allowed a view out of Golgotha’s surface, which looked very far below us. By Forqueray’s estimate we had gained forty-five vertical metres since entering the Spire. Although two hundred further metres lay ahead—the bulk of the climb, in fact—for the first time it began to appear possible that we might succeed. That, of course, was contingent on several assumptions. One was that the problems, while growing steadily more difficult, would not become insoluble. The other was that the doorways would not continue to narrow now that we had discarded the bulky suits.

  But they did.

  As always, the narrowing was imperceptible from room to room, but after five or six it could not be ignored. After ten or fifteen more rooms we would again have to scrape our way between them.

  And what if the narrowing continued beyond that point?

  “We won’t be able to go on,” I said. “We won’t fit—even if we’re naked.”

  “You are entirely too defeatist,” Trintignant said.

  Childe sounded reasonable. “What would you propose, Doctor?”

  “Nothing more than a few minor readjustments of the basic human body-plan. Just enough to enable us to squeeze through apertures which would be impassable with our current . . . encumbrances.”

  Trintignant looked avariciously at my arms and legs.

  “It wouldn’t be worth it,” I said. “I’ll accept your help after I’ve been injured, but if you’re thinking that I’d submit to anything more drastic . . . well, I’m afraid you’re severely mistaken, Doctor.”

  “Amen to that,” Hirz said. “For a while back there, Swift, I really thought this place was getting to you.”

  “It isn’t,” I said. “Not remotely. And in any case, we’re thinking many rooms ahead here, when we might not even be able to get through the next.”

  “I agree,” Childe said. “We’ll take it one at a time. Doctor Trintignant, put your wilder fantasies aside, at least for now.”

  “Consider them relegated to mere daydreams,” Trintignant said.

  So we pushed on.

  Now that we had passed through so many doors, it was possible to see that the Spire’s tasks came in waves; that there might, for instance, be a series of problems which depended on prime number theory, followed by another series which hinged on the properties of higher-dimensional solids. For several rooms in sequence we were confronted by questions related to tiling patterns—tessellations—while another sequence tested our understanding of cellular automata: odd chequerboard armies of shapes which obeyed simple rules and yet interacted in stunningly complex ways. The final challenge in each set would always be the hardest; the one where we were most likely to make a mistake. We were quite prepared to take three or four hours to pass each door, if that was the time it took to be certain—in Celestine’s mind at least—that the answer was clear.

  And though the shunts were leaching fatigue poisons from our blood, and though the modifiers were enabling us to think with a clarity we had never known before, a kind of exhaustion always crept over us after solving one of the harder challenges. It normally passed in a few tens of minutes, but until then we generally waited before venturing through the now open door, gathering our strength again.

  In those quiet minutes we spoke amongst ourselves, discussing what had happened and what we could expect.

  “It’s happened again,” I said, addressing Celestine on the private channel.

  Her answer came back, no more terse than I had expected. “What?”

  “For a while the rest of us could keep up with you. Even Hirz. Or, if not keep up, then at least not lose sight of you completely. But you’re pulling ahead again, aren’t you? Those Juggler routines are kicking in again.”

  She took her time replying. “You have Childe’s medichines.”

  “Yes. But all they can do is work with the basic neural topology, suppressing and enhancing activity without altering the layout of the connections in any significant way. And the ’chines are broad-spectrum; not tuned specifically to any one of us.”

  Celestine looked at the only one of us still wearing one of the original suits. “They worked on Hirz.”

  “Must have been luck. But yes, you’re right. She couldn’t see as far as you, though, even with the modifiers.”

  Celestine tapped the shunt in her wrist, still faintly visible beneath the tight-fitting fabric of her suit. “I took a spike of the modifiers as well.”

  “I doubt that it gave you much of an edge over what you already had.”

  “Maybe not.” She paused. “Is there a point to this conversation, Richard?”

  “Not really,” I said, stung by her response. “I just . . .”

  “Wanted to talk, yes.”

  “And you don’t?”

  “You can hardly blame me if I don’t, can you? This isn’t exactly the place for small talk, let alone with someone who chose to have me erased from his memory.”

  “Would it make any difference if I said I was sorry about that?”

  I could tell from the tone of her response that my answer had not been quite the one she was expecting. “It’s easy to say you’re sorry, now . . . now that it suits you to say as much. That’s not how you felt at the time, is it?”

  I fumbled for an answer which was not too distant from the truth. “Would you believe me if I said I’d had you suppressed because I still loved you, and not for any other reason?”

  “That’s just a little too convenient, isn’t it?”

  “But not necessarily a lie. And can you blame me for it? We were in love, Celestine. You can’t deny that. Just because things happened between us . . .” A question I had been meaning to ask her forced itself to the front of my mind. “Why didn’t you contact me again, after you were told you couldn’t go to Resurgam?”

  “Our relationship was over, Richard.”

  “But we’d parted on reasonably amicable terms. If the Resurgam expedition hadn’t come up, we might not have parted at all.”

  Celestine sighed; one of exasperation. “Well, since you asked, I did try and contact you.”

  “You did?”

  “But by the time I’d made my mind up, I learned about the way you’d had me suppressed. How do you imagine that made me feel, Richard? Like a small, disposable part of your past—something to be wadded up and flicked away when it offended you?”

  “It wasn’t like that at all. I never thought I’d see you again.”

  She snorted. “And maybe you wouldn’t have, if it wasn’t for dear old Roland Childe.”

  I kept my voice level. “He asked me along because we both used to test each other with challenges like this. I presume he needed someone with your kind of Juggler transform. Childe wouldn’t have cared about our past.”

  Her eyes flashed behind the visor of her helmet. “And you don’t care either, do you?”

  “About Childe’s motives? No. They’re neither my concern nor my interest. All that bothers me now is this.”

  I patted the Spire’s thrumming floor.

  “There’s more here than meets the eye, Richard.”

  “What do you mean by that?”

  “Haven’t you noticed how—” She looked at me for several seconds, as if on the verge of revealing something, then shook her head. “Never mind.”

  “What, for pity’s sake?”

  “Doesn’t it strike you that Childe has been just a little to
o well prepared?”

  “I wouldn’t say there’s any such thing as being too well prepared for a thing like Blood Spire, Celestine.”

  “That’s not what I mean.” She fingered the fabric of her skintight. “These suits, for instance. How did he know we wouldn’t be able to go all the way with the larger ones?”

  I shrugged, a gesture that was now perfectly visible. “I don’t know. Maybe he learned a few things from Argyle, before he died.”

  “Then what about Doctor Trintignant? That ghoul isn’t remotely interested in solving the Spire. He hasn’t contributed to a single problem yet. And yet he’s already proved his value, hasn’t he?”

  “I don’t follow.”

  Celestine rubbed her shunt. “These things. And the neural modifiers—Trintignant supervised their installation. And I haven’t even mentioned Forqueray’s arm, or the medical equipment aboard the shuttle.”

  “I still don’t see what you’re getting at.”

  “I don’t know what leverage Childe’s used to get his cooperation—it’s got to be more than bribery or avarice—but I have a very, very nasty idea. And all of it points to something even more disturbing.”

  I was wearying of this. With the challenge of the next door ahead of us, the last thing I needed was paranoiac theory-mongering.

  “Which is?”

  “Childe knows too much about this place.”

  Another room, another wrong answer, another punishment.

  It made the last look like a minor reprimand. I remembered a swift metallic flicker of machines emerging from hatches which opened in the seamless walls: not javelins now, but jointed, articulated pincers and viciously curved scissors. I remembered high-pressure jets of vivid arterial blood spraying the room like pink banners, the shards of shattered bone hammering against the walls like shrapnel. I remembered an unwanted and brutal lesson in the anatomy of the human body; the elegance with which muscle, bone and sinew were anchored to each other and the horrid ease with which they could be flensed apart—filleted—by surgically sharp metallic instruments.

  I remembered screams.

  I remembered indescribable pain, before the analgesics kicked in.