"How long?" I shouted.
"Minutes." Cassian had both hands wrapped around his sword, and I could see the effort it took him not to throw himself at the circle. "At the height of the moon, the binding completes. When it does, he stops being a person."
Above us, through the broken rafters, the blood moon hung exactly in the center of the sky, swollen and red and perfectly round. Beneath it, Marcus floated three feet off the floor, arms spread, head tilted back. The black lines had swallowed his whole body now. Even his eyes had gone white, with a thin black ring running around each one like a hairline crack.
The symbols on the floor turned faster. The nine candle flames burned higher.
"Break it again," Cassian said. "Harder."
"I tried. It swallowed everything."
"Then try something else!"
There is something else, said the voice.
It was so quiet I almost missed it. Quiet, and strange, and carefully neutral, the way you'd speak if you were afraid to be overheard by yourself.
You cannot break a binding with a command. The Tongue commands the world. A binding is part of the world, so it absorbs the command and grows stronger. You need a Word that does not command anything.
What does that mean?
It means a Word that asks the world to forget what it has agreed to. A pause. I can give it to you. But it is not free, David. Nothing in the Tongue is free. And this one is the most expensive Word I have.
I looked at Marcus, at the white of his empty eyes, and heard him again, sitting on that dusty floor with the orange light on his face. Promise me you won't hesitate.
What does it cost?
Something of yours, the voice said. A memory, usually. One that holds weight. I cannot choose which. The blood chooses.
My heart, the slow one, stopped altogether.
"David," Cassian said. His voice had gone very low. "Whatever it is telling you, whatever it is offering, remember that Valerian used the Tongue twice. Both times, it took pieces of him he never got back."
"Is that why you're so scared of it?"
"Yes."
"Then I'm sorry," I said, and meant it.
I stepped up to the edge of the chalk, as close as I could get without crossing, and put both hands flat against the invisible wall. It hummed under my palms like a living thing. Beyond it, Marcus drifted slowly, peacefully, as if he were asleep.
Say it, said the voice. Say it the way I do.
It poured into my mind then, not as sound but as shape, a feeling like a door swinging open at the back of my skull. The Word was long and slow and impossibly old, and when I opened my mouth the whole atrium shook.
"UNDO."
That is only how it sounded in English. In the Tongue it had seven layers, and every one of them ached.
The circle screamed.
White light split the chalk lines. The nine candles guttered, flared, and went out one after another, as if someone were pinching each flame between two fingers. The invisible wall dissolved against my hands, and I fell forward onto my knees, and something went out of me like a breath I would never take again.
I tasted copper. Heat poured from my nose. My ears rang, and my vision swam with red, and then, with a sound like a great glass bell shattering, the circle broke.
Marcus dropped.
I caught him. I don't know how. I was on the floor, and then I was under him, and his full weight slammed into my arms. He was alive. His heart was pounding, fast, frightened, real, and I had never heard anything more beautiful in my life.
The lines on his skin were still there, but they were fading. As I watched, they crawled backward, retreating from his face, his throat, his arms, until his skin was clean and pale and ordinary again.
"Marcus," I whispered. "Hey. Hey. Can you hear me?"
His eyelids fluttered. They were brown. Plain, ordinary, wonderful brown.
"Dude," he croaked. "You're bleeding on me."
I laughed. I couldn't help it. It came out wet and shaky and half a sob.
Cassian knelt beside us, sword forgotten, his gray eyes searching my face. He had gone paler than I'd ever seen him. "That Word," he said hoarsely. "Where did you hear it?"
"The voice taught me."
"No one living knows that Word. Valerian spoke it once, on the night that I—" He stopped, and swallowed whatever came next. "What did it take?"
"Nothing." I wiped my nose with the back of my wrist. "It didn't take anything. I feel fine."
Even as I said it, I knew I was lying. There was a hole in me. Somewhere, I'd lost something, and my mind kept sliding over the place where it used to be, like a tongue sliding over a missing tooth.
Look, said the voice, gently.
I didn't want to look. But I did.
I reached for the memory of my mother's laugh.
It was the thing I always thought of when I was scared. A warm, loud, slightly embarrassing laugh that she'd had since before I could remember, the kind that made strangers turn around in restaurants.
I knew she'd had it. I knew it the way I knew her favorite color and her middle name and the shape of her handwriting.
But I could not remember what it sounded like.
"That is the cost," Cassian said quietly, as if he could see it in my face. "I am sorry."
I nodded. My throat was too tight to speak. Marcus, still half-slumped against my arm, looked from me to Cassian and back again with growing dread.
"What? What did you lose?"
"Nothing important," I said.
He didn't believe me. He opened his mouth to argue, and stopped. His face twisted. "It's still there," he said, rubbing his throat. "The secret. I can hear it, David. The thing it told me about Cassian. I tried to say it just now, and—" He shook his head. "Nothing. It's still locked."
"Then the Hollow is still alive," Cassian said grimly. "And it is still listening."
As if in answer, something moved in the shadows beneath the rafters.
A soft, wet click.
The temperature in the atrium dropped ten degrees. From every dark corner of the ruined room, voices began to whisper. Nurse? Nurse? Nurse? They were quieter now, and slower, and they all came from the same place, a single point near the center of the shattered circle.
Marcus's shadow.
It had stopped moving with him. It lay on the floor, stretched out far too long, its edges rippling. As we watched, it lifted its head.
"Back," Cassian snapped, and hauled both of us toward the wall.
The shadow peeled off the floor. It rose in a long, dripping column, taller than a man, and then it unfolded, joint by joint, until the Hollow stood in the center of the broken circle on its long gray legs, its eyeless face tilted toward the red moon as if it were drinking in the light.
It was missing an arm. The stump was still leaking black fluid where Cassian's blade had taken it.
"Do you know," said the Hollow, in a hundred voices at once, "how long I have waited for someone to be so foolish?"
"You are bleeding," said Cassian coldly. "I would not call that a victory."
"Oh, I am not the one who bled." The smooth, blank face turned toward me, and the slit of its mouth stretched. "He is. Look at him. Look at what he spent to save one small friend. A memory, I think. Something precious. It always is."
My hands tightened on Marcus. "How do you know that?"
"Because I have watched your kind pay it for three thousand years." The Hollow took a slow step toward us, and the floor frosted beneath its feet. "Do you want to know the truth, little king? The circle was never meant to hold him. It was never meant to take the boy."
My stomach dropped. "What?"
"The boy was bait." It tilted its head. "The circle was built to break. Only a Progenitor can break it, and only by speaking the Word that costs the most. I needed you to speak it."
"Why?"
"Because when the circle breaks," said the Hollow, "the door opens. And a door needs only one thing to walk through it."
It smiled. And then it moved.
I have never seen anything so fast. There was no leap, no lunge, no warning. One moment it was ten feet away, and the next its single remaining hand was closing around my throat, its long gray fingers curling cold against my skin.
Cassian's blade came down in a silver arc. The Hollow dissolved into smoke, and the blade passed through nothing. Marcus screamed. I tried to wrench free and found I couldn't breathe, couldn't move, couldn't do anything but look into that smooth, eyeless face and watch the slit of its mouth open wide, wider, wider.
Say a Word, the voice whispered desperately. David. Say anything.
I couldn't. The memory hole in me was a screaming, empty ache, and I had nothing left to pay with.
The Hollow's mouth opened over my face. Inside it was not darkness but a long, white tunnel, and at the end of the tunnel, small and far away, I thought I could see a door. Someone stood in front of it with his back to me. Someone with my shoulders. Someone with my hair.
"Thank you for opening it," it whispered.
It poured into me.
I felt it go in through my mouth, my eyes, my skin, cold and thin and endless, like ice water filling a glass. I heard Cassian shouting. I heard Marcus calling my name. I heard the whispering voices of dead patients rushing through my skull, nurse, nurse, nurse, and then, over them all, a new voice, soft and pleased.
Lovely, said the Hollow, inside my head. A much better door.
The cold receded. The pressure lifted. I fell onto my hands and knees, gasping, with the taste of frost in my mouth.
The atrium was silent.
The Hollow was gone.
"David?" Marcus's voice shook. He crawled toward me, and then froze, staring at my wrist.
I looked down.
Black lines had curled around my left wrist like the beginnings of a bracelet. Three of them. Thin as pencil strokes.
I looked up at Cassian.
He was standing perfectly still in the red light, his sword raised in both hands, the silver edge turned toward my throat. His gray eyes were very bright, and there was something terrible in them. It wasn't hatred. It was grief, the kind a person feels when they've been dreading one moment for four hundred years and it has finally come.
"I made a promise to Valerian," Cassian said softly. "If I ever believed you were becoming what he feared."
"Cassian," Marcus whispered. "Please."
Marcus struggled to his feet, swaying, and put himself between us. He was shaking so hard I could hear his teeth. "Your hand is trembling," he told Cassian. "You don't want to do this."
"Move, boy."
"No."
The silver edge didn't waver, but his knuckles went white on the hilt. For one long heartbeat, the only sound in the ruined atrium was the wind in the rafters and Marcus's ragged breathing.
"I am sorry, David," Cassian said again, softly, to me.
And behind my eyes, the Hollow began, very quietly, to laugh.