“But what’s a day? Who cares about a day?” asked Param.

“Begging your pardon, ma’am,” said Umbo. “We don’t know if it’s a day every time. It might be just a day. But it might be the same proportion. We went back six months, and I returned a little over a day early. A year might be two days off. A thousand years could be more than two thousand days. Eleven thousand years might be twenty-two thousand days. Almost fifty years.”

Param nodded. “But if we’re leaving this wallfold, will that matter?”

“What if we want to come back to this wallfold someday?” asked Rigg. “What if we find a way to break the power of General Citizen? Because I have a feeling that he and Mother are about to remind everybody why the People’s Revolution happened in the first place. What good can we do if we arrive thirty years before we were born?”

“Or three hundred years,” added Umbo, “because it might be random.”

“Or maybe,” said Rigg, “going so very far into the past, he couldn’t move forward again at all, and we’d be stuck there in a world before the human race ever arrived here. It’s an experiment we can’t afford to perform when everything’s at stake.”

“So I stay in the present,” said Umbo, “and send Rigg and Loaf and Olivenko into the past, before the Wall existed. Then they wait for us to pass through the Wall, using your power to be invisible. If we can.”

“What if we can’t? What if the Wall blocks us even in slow time?” asked Param.

“Then I come back across,” said Rigg, “and bring you over, too.”

“Leaving Umbo behind.”

“Without us around,” said Rigg, “Umbo won’t be in any particular danger.”

“What would they care about me?” asked Umbo. He sounded lighthearted, but there was an edge to his voice. It occurred to Rigg that it really bothered Umbo that he was nobody much, in the eyes of history.

“You’re right,” said Rigg. “Nobody cares about you—but that’s because they’re stupid. You’re the most powerful of us. You’re the one who actually travels in time. You’re the one who can change things. The only one.”

Rigg saw Param look again at Umbo. Perhaps it had never occurred to her—raised as she had been in a world where only the royals mattered—that Umbo was anything special. He was a peasant’s son from upriver. But he was also the world’s only time traveler. It wouldn’t hurt Param a bit to realize that nobility of birth meant nothing. It was only what you could do, and chose to do, that made you important or genuinely noble.

They walked only a little further, topping a rise, and Rigg saw that this was the right place. It was not ideal—there were outcroppings of rock, and places that had certainly been eroded by wind-borne sand. But it was a crown of a hill in a dry landscape; no rivers cut through their path. And there were paths of ancient animals crossing right through the Wall, their placement showing that the ground had not changed level very much at all.

“This will do,” said Rigg. “As Loaf said—if it works at all.”

They brought the horses to the very edge of the Wall’s influence and unloaded them. They began grazing on such scant food as they could find.

Rigg climbed up onto an outcropping of rock that gave him a view that extended farther across the Wall. Umbo came up after him. Finally Rigg spotted the distant paths that told him just how far it would take to cross the Wall.

“It’s about a mile,” said Rigg. “Do you see that bent-over scrub oak, next to the spear of rock? When we reach that spot, you can bring us back to the present.”

“That’s more than a mile,” said Umbo.

“Probably,” said Rigg.

“How fast can you walk it, carrying packs?”

“Fast enough. Param will be with you.”

“And what if Param’s ability doesn’t let us go through the Wall after all?”

“Then at least you’ll disappear for a while until they go away.”

“Maybe Param and I should cross first,” said Umbo, “to make sure we can do it.”

“If they weren’t an hour behind us,” said Rigg, “that would be a good idea. But when she’s invisible, she goes very, very slowly. We might be waiting a week for her to bring you across that mile. Or longer.”

“All right then,” said Umbo. “I’ll sit here to watch. Help Param climb up, will you?”

“Saints watch over you,” said Rigg, and started to climb back down.

“Wait,” said Umbo. “Shouldn’t we have some of the provisions?”

Rigg laughed. “Umbo, to you it will be only an hour at the most. However long it takes the two of you to walk a mile together. You won’t get hungry. You won’t even have time to need to pee.”

“I need to pee right now.”

“Well, then, do it off the other side of the rock while I bring her up this one.”

Rigg climbed down and looked for Param.

She was nowhere to be found.

Rigg saw her path and realized that she was testing, after all. But she was moving faster than he had ever seen her go while invisible—which meant that she had actually sped herself up relatively little. He could even glimpse a shimmering in the air where she was, the shape of her—she was at the borders of invisibility.

But it still meant she was moving far more slowly than a normal walk. How far did she intend to go? Because the paths of their pursuers were coming closer all the time, and at the rate they were going, Rigg’s group wouldn’t have a lot of leeway. They needed time to cross the Wall before Umbo would be free to disappear with Param. It was irresponsible of her to use up precious minutes on an experiment. To her she had only been doing this for a minute or two, Rigg was sure. She hadn’t gone more than a few dozen yards into the Wall. How much would she learn from that?

She became visible.

She screamed.

Rigg ran straight for her, as did Olivenko and Loaf.

“I’ll get her!” cried Rigg. “Stay clear!” He already felt the grief and despair and terror filling his heart. He knew that he could never reach her, that all was lost. He knew why she had screamed.

She was staggering toward him, her face a mask of grief and madness. “Run to me!” he shouted. “Don’t disappear again! We haven’t time!”

In a moment he had reached her, but by now the fear was unbearable. His mind kept coming up with reasons for the fear. They were trapped in the Wall and would never get out. The earth would open up and swallow them. General Citizen was already there to kill them. Nothing would work, all would fail.

Param could not have gotten that far if she had been feeling like this as she moved invisibly into the Wall. And she could make it all end by going back into invisibility. But if she did, then there really would be reason to despair. Because by the time she came out of her slow movement, their pursuers would be too close and they’d never make it.

She was stronger than Rigg had feared. For that matter, he was stronger than he had known. Because not only did she not speed up her movement through time in order to end the torment, he did not beg her to, though he longed to.

They took another step, another, and suddenly they could feel the terror fading. Two more steps and they were free of it. Standing with the others.

“I had to know,” said Param. “I had to know if my pathetic little power would let us cross through.”

“Well?” asked Rigg.

“I felt it even in slow time,” said Param. “I thought my ability must have had no influence on it, it was so terrible. But when I returned to real time, it became far worse. Unbearable. As you felt it. So my power did work, and if I slow myself down even more, I think Umbo and I won’t feel it at all. Or not enough to care. And another thing. It doesn’t get worse. It quickly reaches the peak of torment, and continues like that the rest of the way across. That’s when I stopped—when I realized that it wasn’t getting any worse with each step I took. What we experienced there, my brother, I think that was the worst the Wall can do.”