I took a few deep breaths, holding them a handful of seconds each. I looked around. Couldn't see another soul. There was a dot on the distant river under the light patch of sky where the dawn was. It might have been a boat. The ruins spread in every direction. A few were on the horizon, darkly jagged. Towers and bits of domes; bitten, slumped-looking squared things that might once have been tower blocks or big office buildings.

There were some dressed stones sitting half-overgrown by longer gra.s.s a few steps away down the slope towards the nearest marsh.

"Let's sit," Mrs M said. She sat me down on the cold hard stones.

"Where the f.u.c.k is this?" I asked when I had my breathing back to something like normal.

"Another Earth, another Moscow," she said. She sat beside me, half turned to me. The veil was down again, had been ever since we got here.

I rubbed my neck. "Was that the pill did this, or-?"

"This did this," she said, showing me the little lighter gadget. "The pill was for if something went wrong. You had to visualise the room we left from, remember?" I nodded. "That was your way back. You shouldn't need it now, though. We can go back together. The first transition is always the most problematic. We're well attuned." She smiled, patted my arm rea.s.suringly.

"f.u.c.k," I said, shaking my head and standing up again and looking desperately around. I found a fist-sized lump of stone and threw it as hard as I could towards the still-rising spread of light where the dawn was. It disappeared into the gra.s.s downhill with a barely audible thud. I turned back to Mrs M. "No, just give me a minute, okay?"

"I'll stay here," she said, smiling behind the veil and clasping her hands over one raised knee.

I ran down the slope, skidding in places, jumping over a few more of the piles of dark brown stones lying in heaps within the gra.s.s. When the slope levelled out the marsh began and I squelched into muddy water. I put my hand down, brought up some grey-brown mud, stared at it then stared out over the grey landscape and let the mud dribble back through my fingers. A bird made a lonely mewling cry in the distance and another answered from even further away.

It all looked and felt and smelled real as f.u.c.k. The surface of dark water pooling between my shoes black slip-ons! What happened to my Converse? was going still. Looking at my face reflected in it, I didn't even look like myself. My trousers felt coa.r.s.er, and were more like very dark brown than black. No Nokia; nothing in the pockets at all. No Rolex on my wrist, either. I studied my hands. They looked a bit different too. They had freckles. I didn't have freckles, did I? Suddenly I wasn't sure any more. f.u.c.k me, it turned out that I didn't even know the back of my hand like the back of my hand. I turned and saw the small black figure of Mrs Mulverhill sitting where I'd left her. I trudged back up.

"I am able to tandem," she explained as we sat side by side on the stones. A hint of pale yellow-orange sun had peeked out between two layers of cloud to the east. "Some people can. A tandemiser can take one other person with them when they transition. Usually just one. Most people can't transition at all, but of those who can, few can take anything other than themselves from world to world."

"Transition?"

"From one world to another."

"Uh-huh. And you need a pill or something?"

"There is a substance called septus, both in the pill you took and in the spray in here." She brandished the little lighter thing, then secreted it away in the black bandages again somewhere under her ribcage.

I closed my eyes, rubbed my face. When I looked out again, everything was just as it had been. Grey skies, rising sun gleaming all watery, wide marshes, distant black ruins. "So is this like another dimension or something?" I asked. f.u.c.k, I was struggling. I almost wished I'd paid attention in physics lessons.

The whole total bizarre weirdness of this was still affecting me in waves of dizziness, unless it was the drugs I'd swallowed or been injected with. Had there really been no blackout phase? We seemed to have come here from the Novy Pravda between heartbeats, with only that rush of head-turning-inside-out to lead up to it, and that had felt like part of the experience itself rather than something properly separate from it. But had there really been no time to get me properly drugged and able to be shipped out to wherever we were now? It didn't feel like it, but it still had to be more likely, I mean logically, than what Mrs M was telling me.

She shrugged. "This is one of the many worlds," she said. "There are infinities of them. The people I represent travel between them. Sometimes they might need help. Transitioning travelling between worlds is not a perfected process. We would like to employ you to be there to help any travellers blown off-course into your world, as it were, or who would otherwise need help in it. Minor help. Would you do that for us?"

"What exactly do you do? Why are you doing all this travelling, anyway?"

Mrs M made a clicking noise with her mouth. "Nothing that bad, but nothing I can tell you about, either. Nothing that we are doing ought to get you into any legal trouble with your authorities, in the highly unlikely event that they ever find out. You must have heard of the idea of need-to-know?"

"Yeah."

"Well, you don't need to know, so it's best for you not to." A pause while she looked out over the chilly landscape before turning back to me. "Though I suppose I should say that it's not unknown for people to start out doing what we're asking you to do and them then going on to become more actively and operationally involved and even eventually becoming transitioners themselves." That smile behind the lace and dots again. "Not unknown. But one thing at a time, eh? What do you say? Do you think you might accept our offer?"

I stared at her. "I was going to need time to think anyway," I said. "Now, I... I think, I mean... This has given me..." I thought she looked disappointed behind the veil. I sighed. "Oh f.u.c.k, who am I trying to kid? Sure. Yes, of course. Either I've gone f.u.c.king nuts or you've got the keys to the universe in a pill. Or now in a handy spray version."

"Well, the keys to different versions of Earth," she said.

"No other planets?"

"Not as such, yet," she said. "No true time travel, either."

"What about untrue time travel?"

"There is an apparent phenomenon called lag though I suppose it could equally justly be called lead where otherwise near-identical worlds differ only in one being ahead or behind the other, by any interval up to several million years, but it's not a real phenomenon, any more than a celestial constellation is. They remain intrinsically separate and nothing occurring in one directly affects the other."

"Sorry I asked. No aliens?"

"We're still looking."

I paused. "You look a bit alien yourself, Mrs M. No offence."

"None taken. You ready to go back?"

"I think so."

"You may still feel a little disoriented."

"You reckon?"

"You will be finding out something about yourself over the next few days, weeks and months, Adrian."

"Oh yeah?"

"What I said about the pill you took was true, but its other purpose is to give you an excuse to dismiss this as some sort of drug-induced hallucination."

I must have looked sceptical.

Mrs M spread her arms. "Right now you know that this is real and all this has definitely happened. But when you're back in your own body and back in your own world and country and house and job and so on, with life going on as usual, you will start to doubt that any of it was real at all. You may well determine that it did not happen, in which case that is probably what you need to believe to protect your sanity. Or you may accept that it did. Either way this will tell you something about yourself."

"Can't wait." I paused. "Anyway, so long as the money's real. Know what I mean?"

She laughed. A high, tinkly kind of laugh this time. "We try to choose pragmatic, selfish people for such positions, Adrian."

"Selfish, am I?"

"Of course. You know you are. It's not high praise, Adrian, but it's not criticism either. It's just an acknowledgement. All our best people are highly self-centred. It's the only thing that holds them together in the chaos." She grinned. "Anyway. I think you will do very well. Time to go back."

We both stood up. A low breeze ruffled my hair and some of her black bandages. I took a last look round this landscape of watery ruins.

"What happened here, anyway?" I asked.

She looked round briefly. "I don't know," she said. "Something terrible, I should think."

"Yeah," I said. "I should think so too." Even I knew enough history to think of Napoleon and Hitler, and what might have happened in a Third World War.

"Oh," she said, clicking her fingers. "I should warn you."

"What?"

"The selves we left behind, back at the Novy Pravda."

I stared at her. "They're still there?"

"Oh yes. On standby, if you like. Our minds, our true selves are in these bodies, the ones that we happened to find here, but the husks remain where we left them."

I looked at my freckled hand again, then at her. "But you look just like you did."

She smiled behind the black veil. "Well, I am very good at this. And there are infinitudes of worlds to work with. There are even an infinite number where we are having exactly the same conversation as this right now, worlds differing only in one tiny detail which might be an atom of uranium in a deposit deep underground in Venezuela decaying a microsecond earlier than it did here, or a photon in the University of Tasmania taking one slit, not the other, in another running of the two-slit experiment. There may even be an infinite number which are utterly indistinguishable from this one and which are taking place precisely contemporaneously, where the divergence has yet to occur. Though there may not. Partly it depends how you look at it." She gave me a big smile. I'd been looking at her blankly, I guess. "Further research is required," she said. "Anyway, about our other selves, the barely aware husks we left behind."

"Yeah?"

"We may get back to find they are having s.e.x."

I stared at her. "Seriously?"

"When you leave two physically healthy adult humans of each other's preferred gender alone in such close proximity, and they're effectively morons, it tends to happen."

"How romantic."

"Yes. Though it depends. Was it something on your mind before we left?"

"What, you and me having s.e.x?"

"Yes."

"The idea had crossed it."

She tipped her head to one side. "Well, you're not my usual type, but I was finding you moderately attractive, possibly due to the disinhibiting effects of alcohol."

"Don't you get carried away there now, know what I mean?"

She shrugged. "There are couriers who can only take another person with them when they are penetratively conjoined. I have to embrace my fellow traveller. One or two can co-transition just by holding the other's hand. Anyway. We'll see. All I'm saying is, don't be alarmed if we flit back and that's what we're doing."

"Okay," I said. "I'll try not to be alarmed."

She stepped up to me. "Now we embrace, yes?"

My brain felt like it was turning inside out again. Or outside in this time. Whatever. But when we got back I was lying curled up on the floor of the amber-lit room and Mrs M was sitting cross-legged by my side, patting my shoulder and making sorrowful, comforting noises and I had tears in my eyes and a sick feeling in my gut, nursing what felt like a pair of badly bruised t.e.s.t.i.c.l.es, exactly as though somebody had kneed me in the b.a.l.l.s a few minutes earlier.

"Ah," she said. "Sorry. Sometimes that happens, too."

9

Patient 8262

Infinities within infinities within infinities... The human brain quails when confronted with such proliferating vastness. We think we have a grasp of it, brandishing our numbers natural, rational, complex, real, unreal in the face of all that's inestimable, but truthfully these resources are mere talismans, not practical tools. A comfort; no more.

Nevertheless, the doorways into that inexhaustible wilderness of forever multiplying worlds had been opened to us, and we required the means to at least try to understand as much as we could of their hidden mechanisms and how they might be comprehended and navigated.

Learning about the many worlds occurred, appropriately, in layers. One was history. In at least three categories.

There was history that we knew we were allowed to know, history that we knew we were not allowed to know, and history that allegedly didn't exist but that we that is, the students of this effectively measureless subject suspected did exist but was never talked about, not at our level and perhaps not even at the level of the people who taught us.

We were aware from the beginning that the Concern had many more levels than were immediately visible from the lowly strata where we existed in its tortuously convoluted hierarchy, and it was hard even to guess at how far beyond us it extended, given both the irredeemably complex nature of the many worlds themselves and the seemingly quite deliberate opacity of the organisation's structure.

We knew there were various levels and cla.s.ses of executives within l'Expedience with, at the apparent pinnacle of this structure, the Central Council itself, composed of people who knew all there was to know about the Concern's provenance, internal configuration, extent, operational methods and aims, and some of us were of the opinion always perverse, in mine that there might be one central authority figure at the head of all this tiered knowledge and power, a kind of organisational autocrat to whom everybody else was obliged to defer. But for all we knew that final, single, near-G.o.dlike Emperor of the realities if he or she did exist was little better than a foot soldier in a still greater grouping of other Concerns and meta-Concerns extending further and higher out across and through the furiously expanding realities and numbered in millions, billions, trillions... who knew?

For us lowly foot soldiers, though, mere trainees that we were, the centre of our world the centre of all our many worlds was the Speditionary Faculty of the University of Practical Talents, Aspherje, on an Earth that almost uniquely did not call itself Earth, but Calbefraques.

Calbefraques was the ultimate Open world, the mirror image of one of the numberless perfectly Closed Earths where n.o.body knew about the many worlds; a place where possibly every single adult soul who walked its surface knew that it was merely one world within an infinitude of worlds, and a nexus at that, a stepping-off point for as much of that infinitude as it was possible to imagine.

And a world, an Earth that was close to unique. Logically there had to be other versions of this Earth that were close to the Calbefraques that we knew, but we seemed to be unable to access them. It was as though by being the place that could act as a gateway to any other version of Earth, Calbefraques had somehow outpaced all the other versions of itself that would otherwise have existed. It seemed that in the same way that the true consciousness of a transitioner could only be in one world at a time, there could only be one world that was perfectly Open, and that world, that unique Earth was this one, called Calbefraques.

It was here that almost all the transitioners lived when they were not on missions to other worlds, and here too that the vast majority of theorists of transitioning, experts in transitioning, researchers into transitioning and experimental pract.i.tioners of transitioning both made their home and plied their trade. In its globally distributed factories and laboratories all the multifarious paraphernalia of transitioning was manufactured, and somewhere, allegedly the ultimately precious substance we called septus, the drug that made flitting possible in the first place, was brought into being. Exactly how and where this was done and exactly what septus really was, n.o.body seemed to know. The secrecy surrounding the drug's creation was of an order more intense even than that a.s.sociated with the severely security-conscious operations of the Transitionary Corps. Naturally, this meant that the speculation regarding this piece of arcana was, to put it mildly, unrestrained.

There were strict rules about the use and exposure of septus within this world or any other, restricting its use to its flitting-enabling purpose and absolutely nothing else. But it was rumoured that, if one did try to have some of it a.n.a.lysed, in the most advanced laboratories one could find, the sample itself simply vanished, or appeared on inspection by chemical a.n.a.lysis, ma.s.s spectrometry, microscopes working on a variety of wavelengths or any other technique available to be nothing more complicated than pond slime, or even pure water.

Here, in the university that was a city within a city, within its piled pyramids, ziggurats, towers and colonnades, and in the profusion of outlying buildings distributed all across the greater city an ever-multiplying number, in a fit image of what was studied within them millions of students like myself had, over the years, learned as much of that proportion of the truth as it was thought appropriate for us to be allowed to comprehend. What some of us really wanted to know, naturally, was the size of that proportion, and what was concealed in the fraction of it being denied us.

The Transitionary It was the septennial Festival of Death in Aspherje, Calbefraques, and the Central Council of the Transitionary Office had arranged a particularly extravagant party and ball to celebrate both the formal cultural event and the latest expansion and reconst.i.tution of the Council.

Guests arrived on a specially constructed narrow-gauge railway which ran in a loop round the closed city centre, picking up guests from a variety of temporary stations manned by servants dressed as ghouls which were dotted around the periphery of the cordoned-off area, where the guests' own transport had deposited them. The track was lit by tall, smokily guttering torches and by burning braziers hanging from gibbets and made to look like ancient roadside punishment cages, the skeletons of starved miscreants visible through the smoke and flames inside.

At the Final Terminus, the station seemingly made entirely of dinosaur bones where the guests were deposited, a wide moat had been dug across the park in front of the entrance to the University's Great Hall. Beneath the water lay a system of pipes which fed marsh gases and flammable oils to the surface, where they were lit or detonated by floating bundles of burning rags containing clockwork mechanisms that made them jerk and move and appear briefly human.

Guests proceeded across a bridge bowed out across this waste of sporadic conflagration and entered the Great Hall through a recently constructed ill-lit tunnel of soot-blackened stone. Enormous iron doors creaked open to admit guests to a tall circular s.p.a.ce containing another, near-circular moat of unpleasant-smelling water lying at the foot of a great steep bowl of curved walls running with liquids. Across a bridge ahead stood a great wall of what appeared to be slate, its slick surface running with water cascading down its imperfectly vertical surface in fast, hissing waves. Beyond the far end of the bridge, where one might have expected to see a door, there was only this wall of water, nothing else.

The great iron doors behind swung shut on each batch of two dozen or so guests, leaving them looking nervously round, unable to see a way out. Streamers of fire appeared twenty metres above them, all around the top of the vast bowl they found themselves trapped within, while the small bridge that had led them from the tunnel behind was drawn quickly back up to clang and echo against the rust-pitted surface of the doors.

The burning oils quickly covered most of the bowl's curtain wall and started to pool on the surface of the water at the foot, spreading slowly towards the low island of dry stone in the middle where the now-fearful group of guests huddled, beginning to wonder if something had gone wrong with one of the various mechanisms large parts of the university had been closed for months while all this had been set up and there had been rumours of cost overruns, technical problems, project delays and last-minute panics or if it was all some horrendously complicated and involved plot directed at them personally and they were to be cruelly put to death for some real, exaggerated or entirely imaginary crime.

Just when the guests could feel the heat from the wall of flame around them starting to become uncomfortable and were genuinely beginning to fear not just for their costumes but for their lives, the vast wall of slate covered in spilling water ahead of them cracked vertically to reveal itself as a pair of enormous doors which began to open with a crushingly ponderous grace, their burden of water still crashing down their faces undiminished while a broad tongue of stone levered smoothly down between them to provide a bridge over the encircling noose of fire.

Servants dressed as ghosts and the risen dead a few of them equipped with fire extinguishers, just in case beckoned the by now usually highly relieved and indeed cheering partygoers over the stone bridge and into the throat of another dark tunnel which led via almost disappointingly conventional cloak- and restrooms into the main body of the Great Hall, where the ball was to be held under a vast black tent of a roof studded with high and distant lights arranged in starlike constellations.

A short walk away down a corridor lined with skulls gleaned from catacombs across the continent another only slightly smaller hall held a collection of circular drink, food, drug and smoking bars around which people milled like magnetic particles ricocheting within some colossal game. Further away, up some wide steps turned into an uphill slalom slope by dense wavy lines of antique funeral urns, the way led to the great circular s.p.a.ce underneath the Dome of the Mists itself.