I edged around beside him I could see that it reflected not the room but trees, endless deep and dark, moving. The reflection changed gradually as we watched: showing where the wisp had been, I guessed. I held my breath as a shadow moved over the surface: a thing like a walker moving by, but smaller, and instead of the stick-like legs, it had broad silvery grey limbs, veined like leaves. It stopped and turned a strange faceless head towards the wisp. In its forelegs it held a ragged bundle of green torn-up seedlings and plants, roots trailing: for all the world like a gardener who had been weeding. It turned its head from side to side, and then continued onward into the trees, vanishing.
“Nothing,” the Dragon said. “No gathering of strength, no preparations—” He shook his head. “Move back,” he said over his shoulder to me. He prodded the floating wisp back outside the window, then picked up what I had imagined to be a wizard’s staff from the wall, lit the end in the fireplace, and thrust it out directly into the middle of the wisp. The whole floating shimmer of it caught fire in one startling blue burst, burned up, and was gone; a faint sweet smell came through the window: like corruption.
“They can’t see them?” I asked, fascinated.
“Very occasionally one doesn’t come back: I imagine they catch them sometimes,” the Dragon said. “But if they touch it, the sentinel only bursts.” He spoke abstractly; frowning.
“I don’t understand,” I said. “What were you expecting? Isn’t it good that the Wood isn’t preparing an attack?”
“Tell me,” he said, “did you think she would live?”
I hadn’t, of course. It had seemed like a miracle, and one I’d longed for too badly to examine. I hadn’t let myself think about it. “It let her go?” I whispered.
“Not precisely,” he said. “It couldn’t keep her: the Summoning and the purge were driving it out. But I’m certain it could have held on long enough for her to die. And the Wood is hardly inclined to be generous in such cases.” He was tapping his fingers against the window-sill in a pattern that felt oddly familiar; I recognized it as the rhythm of our Summoning chant at the same time he did. He stilled his hand at once. He demanded stiffly, “Is she recovered?”
“She’s better,” I said. “She climbed all the stairs this morning. I’ve put her in my room—”
He made a dismissive flick of his hand. “I thought her recovery might have been meant as a distraction,” he said. “If she’s already well—” He shook his head.
After a moment, his shoulders went back and squared. He dropped his hand from the sill and turned to face me. “Whatever the Wood intends, we’ve lost enough time,” he said, grimly. “Get your books. We need to begin your lessons again.”
I stared at him. “Stop gaping at me,” he said. “Do you even understand what we’ve done?” He gestured to the window. “That wasn’t by any means the only sentinel I sent out. Another of them found the heart-tree that had held the girl. It was highly notable,” he added dryly, “because it was dead. When you burned the corruption out of the girl’s body, you burned the tree itself, too.”
Even then, I still didn’t understand his grimness, and still less when he went on. “The walkers have already torn it down and replanted a seedling, but if it were winter instead of spring, if the clearing had been closer to the edges of the Wood—if we’d only been prepared, we might have gone in with a party of axemen, to clear and burn back the Wood all the way to that clearing.”
“Can we—” I blurted out, shocked, and couldn’t quite make myself even put the idea into words.
“Do it again?” he said. “Yes. Which means that the Wood must make an answer, and soon.”
I began finally to catch his urgency. It was like his worry about Rosya, I suddenly understood: we were in a war against the Wood as well, and our enemy knew that we now had a new weapon we might turn against them. He’d been expecting the Wood to attack not simply for revenge, but to defend itself.
“There’s a great deal of work to do before we can hope to repeat the effects,” he added, and gestured to the table, littered with still more pages. I looked at them properly and realized for the first time that they were notes