"Maybe there's just three," I said hopefully.

I barely got the words out before hiss, clank, release and a fourth monstrosity whomped across the room.

That broke the spell.

Miles grabbed the doork.n.o.b behind us and twisted it frantically. Locked. He put all his weight into it. Nothing. He rammed his ma.s.sive form into the door. It didn't even buckle.

"This," he shouted, poking a thick finger into my chest, "is the last time I listen to you!"

Miles kept slamming his shoulder into the door. I turned to Sarah. Her eyes were locked on the colossal blades, six of them now, mesmerizing. She was paralyzed. This wasn't a room designed to kill. This was a room designed to make you lose your mind. The killing was an afterthought. Another blade dropped, and this time I really felt it--my hair blasted in the breeze.

I grabbed her shoulders and shook her. I shouted her name, but it was hard to hear over the roar. It sounded like a trash compactor closing in on thousands of gla.s.s bottles. I pulled her back. Her feet dragged like she was unconscious. She looked at me blankly. She looked at the blades and started screaming.

I had lost count of them. I yelled at Miles--he was getting nowhere with the door but probably breaking his shoulder.

I saw the image of the demon, grinning at me with those big lips.

Sarah knew something about the demon. She said so.

"Sarah!" I yelled, trying to get her to hear me over the machines. "Sarah, you said it wasn't a totem . . ."

She blinked at me. She shook her head like she couldn't hear me.

"You said we didn't know what we were talking about . . . What is it?"

I turned her toward the mosaic.

"Please, we need to do something."

"I don't know . . ."

"You do. I need you to focus. Come on."

The sound roared and a blade fell so close to us that Miles had to jerk us backward with his ma.s.sive arms.

"We are going to die," I yelled at her.

That did it. Sarah nodded. Her eyes seemed to clear.

"It's not a demon," she said. "It's a homunculus."

Miles roared. "Demon, homunculus, it's the same thing!" He looked at me. "The alchemists made life from scratch. They called them homunculi."

"No," Sarah said, shaking her head vigorously. She had to shout over the machines. "Listen to me. Not alchemy. Biology."

"There's no time," I said. "Can you stop this or not?"

"I don't know," Sarah said. "But I know what he is."

She pointed at the demon.

"Talk fast," I pleaded.

"He . . . it . . . is a map. Of the nervous system. It shows where our nerves are. The more nerves, the bigger you draw the body part."

"What?"

"From neurology . . . the hands, the lips, the genitals . . . that's where we have the most nerves. That's why they look big in the picture. It's a symbol."

"That ugly little s.h.i.t is us?" Miles shouted.

"So what's that?" I asked, pointing to the subway map.

"I knew I'd seen it before," Sarah said. "It's the brachial plexus."

"The what?"

"A map of the nerves in our shoulders and arms. Look. The median nerve. The radial nerve. The ulnar nerve."

We were running out of s.p.a.ce. The door was impossible to see across the room. We had feet left to go.

"Sarah, honey, this has got to get practical really fast."

"It is practical," she said. "Doctors use these maps to figure out where an injury is . . ."

"Like . . ."

And then she saw it. Her eyes literally welled with joy.

"That's it!" she cried.

She pointed.

"Here. See this?"

She jabbed her finger at a missing tile in the subway map, a small hole in the mural.

"So what? It's old."

"No. This isn't an accident. This is what doctors do. This means something."

We heard a hiss and Miles pulled us back. His shoulder slammed against the back wall, just as another blade swung past.

"What, Sarah?"

"If someone got hurt, here--" She pointed to the gap in the mural. "If this nerve got severed . . . you'd have a specific injury . . . I need to think . . ."

"NO TIME!".

". . . C5, C6, C7 . . .".

"Come on, Sarah . . ."

". . . roots . . . then trunks . . . then divisions . . ."

"Come on."

". . . splits to the median nerve and crosses . . ."

"COME ON".

". . . you'd lose sensation in . . . in . . ."

She was squeezing her eyes shut and shaking her head.

Miles pressed himself flat against the back wall and yelled, "Why do I have to be so f.u.c.king fat?"

The next blade would pin us all.

She cried: "He'd go numb in the lateral three-and-one-half fingers of his right hand!"

She bolted across the room toward the homunculus.

I heard the rumbling of the next machine. There was a flash of silver. Behind me the blade came free, split the subway or the brachial plexus or whatever the f.u.c.k it was and tore at me. I jumped. The blade flew toward Sarah. It would split her in half.

"SARAH!".

She dove to the floor and slammed her fingers toward the demon. The noise was unbearable. I hit the wall, saw flashes of light, and moaned and rolled over onto my side to see her reach the demon and press the shiny tiles of his outer four fingers. They sank inward with a click and she screamed or laughed and rolled to her side as the blade ripped past.

It disappeared into the wall and a tremendous clamping sound rang out. It didn't come back out. All down the room the blades swung on their paths into the walls and didn't come out again. The noise decreased with each return, until one or two last blades disappeared and it was totally, unnaturally silent. There was only the smell of rank gasoline and the total absence of thought in my head--perfect stillness.

At the far end of the room, the door had slid open.

I felt a joy surging inside me.

Sarah was on her feet. She was okay. She was smiling at me and tears were streaming down her face. She put her hand on my cheeks and I realized I was crying too. I grabbed her and hugged her tighter than I've ever hugged anyone, and I just kept saying Oh my G.o.d, Oh my G.o.d in her ear, over and over. Then I felt the crushing hug of Miles around us.

"You did it!" he cried to Sarah. "My G.o.d you f.u.c.king did it! What did you do?"

Sarah beamed. "It's just science." She pointed at the brachial plexus. "It's a map of the nerves in someone's arm. This missing tile, here, it's intentional, like someone severed the nerve. I just had to figure out where a person would go numb if you cut that specific nerve."

"Oh," Miles said. "I knew that."

Sarah was smiling and we ran toward the door. "Let's get out of this room," she said, laughing. She took off, Miles behind her, me last.

And that's when the bad thought came into my head, so quickly that I didn't even see it at first. It was just a sensation. We ran toward the door.

I felt the thought unpacking itself. I became aware of it, of what it was trying to tell me. I couldn't verbalize fast enough. Sarah was at the door, running through it. Miles was on her heels, his momentum vast. I couldn't get the words out fast enough, but my arm just shot forward and grabbed at them.

Why hadn't I seen it sooner? It was so obvious. Three rooms. Three puzzles. The first one logic: the two kings. A lawyer's puzzle. The second: the Ship of Theseus. A philosopher's riddle. The third, the homunculus--only for a neurologist could that puzzle exist. Three of us--a lawyer, a philosopher, a neurosurgeon.

Oh G.o.d, they were just waiting for us.

My hand closed over a shirt, and with the strength that only terror can give you, I pulled back and Miles came with me as Sarah disappeared through the door.

I fell backward and Miles came down, half on top of me, crushing the wind out of me.

A second later, I heard Sarah scream.

36.

I pushed Miles off me and ran to the edge of the door. I expected to see Sarah, to figure out some way to help her. But what I saw instead was a hole in the floor, and a giant trapdoor hanging down. And below that, emptiness. Just a vast hole that sloped down at a steep angle into nothing. The false floor was long. She would have made it several feet into the room before it collapsed below her and sent her spiraling down.

I tried to see down into the hole. I got on my hands and knees and let myself hang over it. Cool, earthy air hit my face. But I couldn't see more than a few feet. The chute just disappeared into blackness.

I felt my world start to unravel. There was a gnawing sensation in my brain that made me want to start shaking my head like a wandering lunatic. I shouted Sarah into the hole. My voice echoed down and back again and mocked me. But nothing real came back. No call for help. Not her soft voice, calling my name. I yelled again. Nothing.

That's when I felt Miles's hand on my shoulder.

"Jeremy."

I was hanging too deep into the hole, holding on with my hands and trying to see something, anything. Miles pulled me back.

"You're gonna fall," he said.

The room was tiny. Just big enough to get the three of us to the middle, on our way to a door at the far end, before the trap sprung. There were candles burning in holders on the walls, the room flickering between shadows and light.

Miles asked how I realized it was a trap. I told him about the puzzles, the way each one was designed for one of us. Like they wanted us to solve them.

Miles shook his head. It was a gesture I'd seen before: a mix of surprise and admiration for the V&D and their tricks--except that this time, there was less surprise, less admiration, crowded out by something I'd never seen in Miles's face before: defeat. He looked defeated.

"It was a test," he said. His eyes were sad. "A final warning. If we were smart enough to get it, we were smart enough to turn around and honor our deal. And if not . . ." He looked at the trapdoor. "Then they'd have to handle us another way."

I stepped toward Miles.

"What are you saying?"

"Jeremy . . ."

"What are you saying?"