“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. Fuck, 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 fuck, who am I trying to kid? Sure. Yes, of course. Either I’ve gone fucking 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 sex.”

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 sex?”

“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.”