He finally let me stop for a rest at noon. I crumpled into a chair, hedgehog-prickled and exhausted; the barriers had held, but I felt very much as though I’d been jabbed repeatedly with sharp sticks. I looked down at the old vellum, so carefully sealed away, with the strange-shaped letters; I wondered how old it was.

“Very old,” he said. “Older than Polnya: it might even be older than the Wood.”

I stared at him; it hadn’t occurred to me even to think, before then, that the Wood hadn’t always been here, always been what it was.

He shrugged. “For all we know, it has. It’s certainly older than Polnya and Rosya: it was here before this valley was ever settled by either of us.” He tapped the parchment in the glass. “These were the first people who lived in this part of the world, so far as we know, some thousand years ago. Their sorcerer-kings brought the tongue of magic west with them, from the barren lands on the far side of Rosya, when they first settled this valley. And then the Wood rolled over them, brought their fortresses low and laid their fields waste. There’s little left of their work now.”

“But,” I said, “if the Wood wasn’t here when they first settled the valley, where did it come from?”

The Dragon shrugged. “If you go to the capital, you’ll find any number of troubadours who will be happy to sing you the rising of the Wood. It’s a popular subject among them, at least when they have an audience that knows less about it than they do: it offers them enormous scope for creativity. I suppose there’s a chance one of them has hit on the true story. Light the fire and let’s begin again.”

It wasn’t until late that evening, as the light was failing, that he was satisfied with my work. He tried to send me to bed, but I wouldn’t have it. Wensa’s words still grated and scraped in the back of my head, and it occurred to me that perhaps he’d wanted me exhausted so he could put me off for another day. I wanted to see Kasia with my own eyes; I wanted to know what I was facing, this corruption I had to find a way to fight. “No,” I said. “No. You said I could see her when I could protect myself.”

He threw up his hands. “All right,” he said. “Follow me.”

He led me to the bottom of the stairs, and into the cellars past the kitchen. I remembered searching all those walls in desperation, when I’d thought he was draining my life; I had run my hands over every wall, poked my fingers into every crack, and tugged on every worn brick, trying to find a way out. But he led me to a smooth-polished part of the wall, a single entire slab of pale white stone unbroken by any mortar. He touched it lightly with the fingers of one hand and crooked them up like a spider; I felt the faint thrill of his magic working. The whole slab swung back into the wall, revealing a stairwell of the same pale stone, shining dimly, that bent steeply downwards.

I followed him down the passage. It was different from the rest of the tower: older and more strange. The steps were hard-edged on either side but worn in the middle to softness, and letters had been carved in a line running along the base of both walls, a script neither ours nor Rosyan: very much like the shape of the letters on the parchment with the protection spell. We seemed to go down for a long time, and I was increasingly aware of the weight of stone around us, of silence. It felt like a tomb.

“It is a tomb,” he said. We had reached the bottom of the stairs, coming into a small round room. The very air seemed thicker. The writing came off one wall of the stairwell, continued all around it in an unbroken line that circled to the opposite side, went up the wall in a tall curve that drew an arch, and then came back and went up the other side of stairs. There was a small patch of lighter stone inside the arch, towards the bottom—as though the rest of the wall had been built, and then had been closed up afterwards. It looked perhaps the size for a man to crawl through.

“Is—is someone still buried here?” I asked, timidly. My voice came out hushed.

“Yes,” the Dragon said. “But even kings don’t object to sharing once they’re dead. Listen to me now,” he said, turning to me. “I’m not going to teach you the spell to walk through the wall. When you want to see her, I’ll take you through myself. If you try to touch her, if you let her come in arm’s reach of you, I’ll take you out again at once. Now lay on your protections, if you insist on doing this.”

I lit the small handful of pine needles on the floor and made the chant, putting my face in their smoke, and then I put my hand in his, and let him draw me through the wall.

He’d made me fear the worst: Kasia as tormented as Jerzy, foaming-mouthed and tearing at her own skin; Kasia full of those slithering corrupted shadows, eating away at everything inside her. I was prepared for anything; I braced myself. But when he brought me through the wall, she was only sitting huddled and small in the corner on a thin pallet, her arms around her knees. There was a plate of food and water on the floor next to her, and she’d eaten and drunk; she’d washed her face, her hair was neatly plaited. She looked tired and afraid, but still herself, and she struggled up to her feet and came to me, holding out her hands. “Nieshka,” she said. “Nieshka, you found me.”

“No closer,” the Dragon said flatly, and added, “Valur polzhys,” and a sudden line of hot flame leapt up across the floor between us: I’d been reaching towards her without being able to help it.

I dropped my hands to my sides and clenched them into fists—and Kasia stepped back, too, staying behind the fire; she nodded obediently to the Dragon. I stood staring at her, helplessly, full of involuntary hope. “Are you—” I said, and my voice choked in my throat.

“I don’t know,” Kasia said, her voice trembling. “I don’t—remember. Not anything after they took me into the Wood. They took me into the Wood and they—they—” She stopped, her mouth open a little. There was horror in her eyes, the same horror I’d felt when I’d found her in the tree, buried beneath the skin.

I had to stop myself reaching out to her. I was in the Wood again myself, seeing her blind, choked face, her pleading hands. “Don’t speak of it,” I said, thick and miserable. I felt a surge of anger at the Dragon for holding me back this long. I had already made plans in my head: I would use Jaga’s spell to find where that corruption had taken root in her; then I would ask the Dragon to show me the purging spells he’d used on me. I would look through Jaga’s book and find others like it, and drive it out of her. “Don’t think of it yet, just tell me, how do you feel? Are you—sick, or cold—”