That evening she was already waiting when he brought his slate out into the garden. “We must talk,” he wrote. “I know ways out of this house . . . if we can get into the passages . . . one of them leads to the library . . . We can hide there to talk . . . very quick talks so no one notices we’re gone.”

Then he erased “we’re” and replaced it with “I’m,” since no one would know whether she was missing or not.

That night he tried not to sleep, hoping she would come again and he might see her. But sleep overcame his plans, and he woke with someone jostling his shoulder. As he stirred, a hand lightly touched his lips. He opened his eyes. It was a woman’s shape, but he couldn’t make out a face.

He got up silently and followed her. She moved unerringly, keeping to her habit of walking near the edge of each corridor and skirting around the borders of each room. She seemed to know the routines of the night quite perfectly—and why wouldn’t she? They encountered no one.

Finally they were in a rarely used corridor that led to some guest rooms. She stopped, and Rigg approached her. “Param?” he whispered softly.

In reply, she embraced him and whispered in his ear, “O my brother, he said that you would come.”

In that moment Rigg realized that Father must have come to her, as he had come to Umbo and Nox, and helped her learn to control and use her power. For who else could have promised her anything about Rigg? Who else knew that he existed? Yet had Father ever been gone from Fall Ford without Rigg long enough to come to Aressa Sessamo and return again? Rigg knew it would be foolish to think that anything was impossible to Father. In a world where Rigg, Umbo, Param, and Nox had such odd powers, who knew what Father was capable of?

“There’s an entrance to the unused passages not far from here,” he whispered back.

She gave him her hand, and he led her to the place. He could see old paths as they moved through what now seemed to be solid wall. As he had done before, he passed a hand all the way around the aperture, but couldn’t find any sign of it.

She touched his shoulder and drew him away. “There’s really a door there?” she whispered.

“There was. But not used in two hundred years.”

“So the wall cannot be stone or cement or brick,” she said.

“It’s an interior wall. I assume that even if they sealed it up, it would still be lath-and-plaster or wood. But I don’t know. Does it matter? It might be light enough that we could kick it in—but then we could never close it behind us.”

In reply, she pushed him gently against the opposite wall of the corridor: Stay, the gesture meant. He watched as she quickly faded, then stood patiently waiting as she passed into the wall, her path echoing exactly the paths of the people who had once used this passage.

On the other side of the wall, he couldn’t tell what she was doing. But after a while, he heard the faintest thud and then a ping, as if a long unused spring had been forced into service after the loosing of a latch. To his surprise, instead of a doorway opening in the wall, the whole section of wall between support posts rose up smoothly, revealing a passage behind it—with Param there waiting.

Rigg stepped through into the passage. Param worked a lever and the wall slid silently back down. No wonder Rigg hadn’t been able to find a door. Just one of the limitations of his gift. He could tell where people had passed, but not what the place had looked like when they came through.

Rigg had expected the passage to be dark, but there was a faint silvery light. He made his way toward the seeming source of the light, wondering if there was some exterior vent that let in the ringlight.

It was soon clear that the light came from a mirror, which was reflecting light from another mirror—beyond that Rigg could not see how many other bends there might be. The light in this space was ringlight. On a cloudy night, this passage would require a candle—or such knowledge of it as would allow someone to pass through it in the dark.

“Did it hurt you?” he asked. “To go through the wall? Or door, or whatever it is?”

“Yes,” she said. She held out a hand. He touched it and recoiled. She was hot, like a child with a bad fever. He touched her forehead, her cheek. Hot all over.

“You can’t do that ever again,” he said.

“I have to,” she said. “I have no idea how to open it from the outside. But it’s not that bad. I cool down soon enough. It’s not like stone or brick—stone burns me, my clothing catches fire. I have to watch to make sure I never brush against stone when I’m hiding.”

In reply he hugged her. “You have no idea what it meant to me, to know I had a sister.”

“And to me,” she said. “He told me never to tell Mother that I knew about you. But you were coming and you would set me free.”

“I will,” he said. “I know how to follow these passages to get through the outside wall.”

“Under it?” she asked.

“The land these houses are built on was raised. It’s not as high now, because the weight of the houses presses it down. So some of the passages may have water in them now—this is the river delta, and water is just below the surface everywhere. But as long as we can breathe, we can make it out of here. One long passage leads to the Library of Nothing.”

“How can you know this? Have you gone into these passages before?”

“No,” said Rigg. “But I’ve seen the paths of the people who’ve used them. I know where they went. That’s what I do—I see their paths, even when they’re hidden behind walls or underground.”

“You have a much more useful gift than mine,” she said.

“Mine didn’t get me into this space. Mine doesn’t allow me to disappear in plain day.”

“Yours doesn’t burn you up when you pass through things.”

“I’m sorry I walked through you that time.”

“It wasn’t bad,” she said. “We were both moving—it means we didn’t occupy the same space for very long. Walls are stationary. I’m the only one moving, and the contact lasts a lot longer.”

He held her hands tightly. “What did you call him? The man I knew as Father?”

“Walker,” she said.

“So he was in this house?”

“Yes,” she said. “I told Mother that one of the scholars had inadvertently helped me understand my gift. But really he came here as a gardener. The gardens still show his touch. Why didn’t you know he was here? Couldn’t you see his path?”

“Father—Walker—he doesn’t make a path. He has no path.”

“How could he manage that?”

“I don’t know if he manages it or simply doesn’t have one. He’s a saint, I think. A hero. He has powers other people don’t have.”

“But when I was invisible, he couldn’t see me, the way you can.”

“I can’t see you, I can only see where you were—the spot you passed through and left behind a moment before. And it isn’t seeing, exactly. I can close my eyes or turn my back and still find your path.”

“He said you were the best of us.”

“Us?”

“All his students.”

“So he told you about others?”

“He said the world has bent itself to make us. These powers run strong in this wallfold, he said. So everything depends on us.”

“What everything?” asked Rigg. “Restoring the monarchy? I don’t really care about that.”

“Neither do I,” she said. “Neither did he.”

“He told you so much,” said Rigg. “He told me nothing.”

“Are you jealous?”

“Yes,” he said. “And angry. Why didn’t he trust me?”

“He trusted you most of all, he told me that. He said you were the most ready. His best student.”

“I can’t do anything myself. I can see paths, yes, but I can’t do anything without Umbo—he’s the one who actually lets me move back in time. The way you got me in here. I can’t do anything myself.”

“You knew where this passage was.”

Rigg realized they were wasting time on reassurances that his own gift had value. “We don’t have very long. Someone’s going to notice we’re gone.”