One day, working in the kitchen, she accidentally solved a problem that had continued to nag at her.

She was stacking away some of the clean crockery in a metal cupboard used for this purpose, when something about it caught her attention. It had been changed almost out of recognition — its components had been removed, and it had been fitted with wooden shelves — but the IBM motif on one of the doors still showed through the covering layer of paint.

When she could, Elizabeth walked around the rest of the city, curious about almost everything she saw. Before entering the city she had expected to find herself a virtual prisoner, but beyond the bounds of the duties she had to perform she was free to go wherever she liked, do whatever she wished. She talked to people, she saw, she registered, and she thought.

One day she came across a small room set aside for use by the ordinary people of the city in their leisure hours. Lying on a table she found a few sheets of printed paper, neatly stapled together. She glanced at them without much interest, saw the title on the first page: Destaine’s Directive.

Later, as she walked through the city she saw many more of these printed sheets, and in due time, with her curiosity piqued, she read one set through. Having seen its contents, she immediately concealed a copy in the bedclothes of her bunk, meaning to take it with her when she left the city.

She was beginning to understand… She returned again to Destaine, read his words so often they became almost photographically recorded. And she thought about Helward, and his apparently wild behaviour and words, and she tried to remember what he had said.

In time, a kind of logical pattern appeared… but there was one ineradicable flaw in everything.

The hypothesis by which the city and its people existed was that the world on which they lived was somehow inverted. Not only the world, but all the physical objects in the universe in which that world was supposed to exist. The shape that Destame drew — a solid world, curved north and south in the shape of hyperbolas — was the approximation they used, and it correlated indeed with the strange shape that Helward had drawn to depict the sun.

One day Elizabeth saw the flaw, as she walked through one of the parts of the city presently being re-built.

She glanced up at the sun, shielding her eyes with her hand. The sun was as she had ever known it: a brilliant white ball of light high in the sky.

7

Elizabeth planned to leave the city the following morning, taking one of the horses and riding across country to the village. From there she could get back to headquarters and take some leave. She was due for some leave in a few weeks’ time, and she knew she could have it brought forward without much difficulty. With the four weeks then available, she would have plenty of time to get back to England and try to find some authority somewhere who could be made interested in what she had discovered.

She did not wish to draw attention to herself once she had formed this plan, and so spent the day working in the kitchens as normal. In the evening she went to the reception room.

When she walked through the door, the first man she saw was Helward. He was standing with his back to her, talking to one of the transferred girls.

She went and stood behind him.

“Hello, Helward,” she said quietly.

He turned round to acknowledge her, then looked at her in amazement.

“You!” he said. “What are you doing here?”

“Ssh! I’m not supposed to be able to speak English very well. I’m one of your transferred women.”

She walked over to a deserted part of the room. The woman at the bar nodded her head in patronizing approval as Helward followed.

“Look,” Elizabeth said at once, “I’m sorry about the last time we met. I understand better now.”

“And I’m sorry if I frightened you.”

“Have you said anything to any of the others?”

“About you being from Earth? No.”

“Good. Don’t say anything.”

He said: “Are you really from Earth planet?”

“Yes, but I wish you wouldn’t refer to it as that. I’m from Earth, and so are you. There’s a misunderstanding.”

“God, you can say that again.” He looked down at her from the nine inches advantage he had in height. “You look different here… but what are you doing as a transfer?”

“It was the only way of getting into the city I could think of.”

“I would have taken you.” He glanced around the room. “Have you paired up with any of the men yet?”

“No.”

“Don’t.” As he talked, he kept looking over his shoulder. “Have you got a room to yourself? We could talk better.”

“Yes. Shall we go?”

She closed the door when they were inside the room; the walls were thin, but at least it had the appearance of privacy. She wondered why he needed to be guarded in speaking to her.

She sat on the chair, and Helward sat on the edge of the bed.

“I’ve read Destaine,” she said. “It was fascinating. I’ve heard of him somehow. Who was he?”

“The founder of the city.”

“Yes, I’d gathered that. But he was known for something else.”

Helward looked blank. “Did what he write make any sense to you?”

“A little. He was a very lost man. But he was wrong.”

“Wrong about what?”

“The city, and the danger it was in. He writes as if he and the others had somehow been transported to another world.”

“That’s so.”

Elizabeth shook her head. “You’ve never left Earth, Helward. As I sit here and talk to you now, we’re both on Earth.”

He shook his head in despair. “You’re wrong, I know you’re wrong. Whatever you say, Destaine knew the true situation. We are on another world.”

Elizabeth said: “The other day… you drew me with the sun behind me. You drew it like a hyperbola. Is that how you see it? You drew me too tall. Is that how you see me?”

“That’s not how I see the sun, that’s how it is. And it is how the world is. You I drew tall, because… that’s how I saw you then. We were a long way north of the city. Now… It’s too difficult to explain.”

“Try it.”

“No.”

“O.K. Do you know how I see the sun? It’s normal… round, spherical, whatever the correct description is. Can’t you see that it’s a question of what we ourselves perceive? Your perceptions inform you incorrectly… I don’t know why, but Destame’s perception was wrong too.”

“Liz, it’s more than perception. I’ve seen, felt, lived in this world. Whatever you say, it’s real to me. I’m not alone. Most of the people in the city carry the same knowledge. It started with Destaine because he was there at the beginning. We’ve survived here a long time, simply because of that knowledge. It’s been the root of everything, and it’s kept us alive because without it we would not keep the city moving.”

Elizabeth started to say something, but he carried on. “Liz, after I saw you the other day I needed time to think. I rode north, a long way north. I saw something there that is going to test the city’s capacity for survival like it has never been tested before. Meeting you was… I don’t know. More than I had expected. But it led indirectly to a much bigger thing.”

“What is it?”

“I can’t tell you.”

“Why not?”

“I can’t tell anyone, except the Navigators. They’ve declared it restricted for the moment. It would be a bad time for the news to get out.”

“What do you mean?”

“Have you heard of the Terminators?”

“Yes… but I don’t know who they are.”

“They’re a… political group in the city. They’ve been trying to get the city to stop. If this news leaked out at the moment, there’d be a lot of trouble. We’ve just survived a major crisis, and the Navigators don’t want another.”

Elizabeth stared at him without saying anything. She had suddenly seen herself in a new light.