"To some extent."

She smiled. "And 'to some extent' is all I follow myself. One thing the Guild always tells new members — 'There are no experts where Time is concerned'. All we seek to do is to survive, to explore, to make occasional discoveries. Yet there is a particular theory which suggests that with every one discovery we make about Time, we create two new mysteries. Time can never be codified, as Space can be, because our very thoughts, our information about it, our actions based on that information, all contribute to extend the boundaries, to produce new anomalies, new aspects of Time's nature. Do I become too abstract? If so, it is because I discuss something which is numinous — unknowable — perhaps truly metaphysical. Time is a dream — or a nightmare — from which there is never any waking. We who travel in Time are dreamers who occasionally share a common experience. To retain one's identity, to retain some sense of meaning in one's own life, that is all the time-traveller can hope for — it is why the Guild exists. You are lucky that you are not adrift in the multiverse, as Captain Bastable was, for you can become like a drowning man who refuses to float, but flounders — and every wave which you set up in the Sea of Time has a habit of becoming a whole ocean in its own right."

Mrs. Underwood had listened, but she was disturbed. She lifted the lid of the hamper and opened an air-tight tin, offering Mrs. Persson a brandy-snap.

They munched.

"Delicious," said Mrs. Persson. "After the twentieth, the nineteenth century has always been my favourite."

"From what century are you originally?" Jherek asked, to pass the time.

"The twentieth — mid-twentieth. I have a fair bit to do with that ancestor of yours. And his sister, of course. One of my best friends." She saw that he was puzzled. "You don't know him? Strange. Yet, Jagged — your genes…" She shrugged.

He was, however, eager. Here could be the answer he had sought from Jagged.

"Jagged has refused to be frank with me," he told her, "on that very subject. I would be grateful if you could enlighten me. He has promised to do so, on our return."

But she was biting her lip, as if she had inadvertently betrayed a confidence. "I can't," she said. "He must have reasons — I could not speak without first having his permission…"

"But there is a motive," said Mrs. Underwood sharply. "It seems that he deliberately brought us together. We have had more than a hint — that he could be engineering some of our misfortunes…"

"And saving us from others," Jherek pointed out, to be fair. "He insists disinterest, yet I am certain…"

"I cannot help you speculate," said Mrs. Persson. "Here comes Captain Bastable with the boat."

The small vessel was bouncing rapidly towards them, its engine shrieking, the water foaming white in its wake. Bastable made it turn, just before it struck the beach, and cut off the engine. "Do you mind getting a bit wet? There are no scorpions about."

They waded to the boat and pulled themselves aboard after dumping the hamper into the bottom. Mrs. Underwood scanned the water. "I had no idea creatures of that size existed … Dinosaurs, perhaps, but not insects — I know they are not really insects, but…"

"They won't survive," said Captain Bastable as he brought the engine to life again. "Eventually the fish will wipe them out. They're growing larger all the time, those fish. A million years will see quite a few changes in this creek." He smiled. "It's up to us to ensure we make none ourselves." He pointed back at the water. "We don't leave a trace of oil behind which isn't detected and cleaned up by one of our other machines."

"And that is how you resist the Morphail Effect," said Jherek.

"We don't use that name for it," interjected Mrs. Persson, "but, yes — Time allows us to remain here as long as there are no permanent anachronisms. And that includes traces which might be detected by future investigators and prove anachronistic. It is why we were so eager to rescue that tin cup. All our equipment is of highly perishable material. It serves us, but would not survive in any form after about a century. Our existence is tentative — we could be hurled out of this age at any moment and find ourselves not only separated, perhaps for ever, but in an environment incapable, even in its essentials, of supporting human life."

"You run great risks, it seems," said Mrs. Underwood. "Why?"

Mrs. Persson laughed. "One gets a taste for it. But, then, you know that yourself."

The creek began to narrow, between lichen-covered banks, and, at the far end, a wooden jetty could be seen. There were two other boats moored beside it. Behind the jetty, in the shadow of thick foliage, was a dark mass, man-made.

A fair-haired youth, wearing an identical suit to those worn by Mrs. Persson and Captain Bastable, took the mooring rope Mrs. Persson flung to him. He nodded cheerfully to Jherek and Mrs. Underwood as they jumped onto the jetty. "Your friends are already inside," he said.

The four of them walked over lichen-strewn rock towards the black, featureless walls ahead; these were tall and curved inward and they had a warm, rubbery smell. Mrs. Persson took off her helmet and shook out her short dark hair; she had a pleasant, boyish look. Her movements were graceful as she touched the wall in two places, making a section slide back to admit them. They stepped inside.

There were several box-shaped buildings in the compound, some quite large. Mrs. Persson led them towards the largest. There was little daylight, but a continuous strip of artificial lighting ran the entire circumference of the wall. The ground was covered in the same slightly yielding black material and Jherek had the impression that the entire camp could be folded in on itself within a few seconds and transported as a single unit. He imagined it as some large time-ship, for it bore certain resemblances to the machine in which he had originally travelled to the nineteenth century.

Captain Bastable stood to one side of the entrance allowing first Mrs. Persson and then Mrs. Underwood to enter. Jherek was next. Here were panels of instruments, screens, winking indicators, all of the primitive, fascinating kind which Jherek associated with the remote past.

"It's perfect," he said. "You've made it blend so well with the environment."

"Thank you." Mrs. Persson's smile was for herself. "The Guild stores all its information here. We can also detect the movements of time-vessels along the megaflow, as it's sometimes termed. We did not, incidentally, detect yours. Instead there was a sort of rupture, quickly healed. You did not come in a ship?"

"Yes. It's somewhere on the beach where we left it, I think."

"We haven't found it."

Captain Bastable unzipped his overalls. Underneath them he wore a simple grey military uniform. "Perhaps it was on automatic return," he suggested. "Or if it was malfunctioning, it could have continued on, moving at random, and be anywhere by now."

"The machine was working badly," Mrs. Underwood informed him. We should not, for instance, be here at all. I would be more than grateful, Captain Bastable, if you could find some means of returning us — at least myself — to the nineteenth century."

"That wouldn't be difficult," he said, "but whether you'd stay there or not is another matter. Once a time-traveller always a time-traveller, you know. It's our fate, isn't it?"

"I had no idea…"

Mrs. Persson put a hand on Mrs. Underwood's shoulder. "There are some of us who find it easier to remain in certain ages than others — and there are ages, closer to the beginnings or the ends of Time, which rarely reject those who wish to settle. Genes, I gather, have a little to do with it. But that is Jagged's speciality and he has doubtless bored you as much as he has bored us with his speculations."