We followed the map, using a small compa.s.s of Sarah's from her father. He was a tyc.o.o.n of some kind at a Boston investment bank that had started three hundred years ago as a maritime trading company. In a nod to the past, they gave nautical compa.s.ses to their new executives, and he had given his to Sarah when she graduated from medical school. This was the first time she'd taken it out of its leather pouch, which gave her a perverse satisfaction, under the circ.u.mstances.

The steam tunnels seemed darker now. Somewhere outside, a cold front was pulling the temperature down to minus four--a cold so extreme that all life seemed to pause--and the maintenance lights, usually so bright, were pulsing dimly as the campus struggled to heat itself. The only sound was the occasional hiss or drip far down the tunnel, and of course the slap of our feet, which we tried to keep to a minimum. I thought of the Puppet Man. Sarah was next to me. Miles lagged behind, his leather satchel over his shoulder. He was the only one who seemed totally at ease. He might as well have been strolling to a Phish concert.

I looked at the map in my hands and thought with a shiver: two of the three people who contributed to this are dead--Frank Shepard for about two hundred years, Chance Worthington for about two days. I was the only one whose name was still ticked in the Alive column.

We pa.s.sed under Creighton and Worley. We knew we were under the Michaelson Chemistry Labs when the vapors. .h.i.t us through the air vents overhead, and we pa.s.sed a trash heap of old beakers and Erlenmeyer flasks, all shattered and discarded--a tribute to two centuries of clumsy students. We arrived below Embry House and took fork after fork to place ourselves directly below the Steel Man. I tried to hear the thumping of music as we pa.s.sed beneath that famed party room--I imagined the beautiful people dancing in the style of my generation, rugby players and sorority sisters grinding against each other five floors above us.

And then, at the end of our map, we saw a door. It was one of many in a small deserted hallway. We were in a branch of a branch of a branch of the tunnels. No one would ever come this way unless they knew exactly what they were looking for.

We almost pa.s.sed it.

It would've been an ordinary door, identical to dozens of utility closets and electrical rooms we'd already pa.s.sed, except for the subtle glyph above the door frame: Two small eyes--orange pupils and black irises--staring down at us.

I gave the k.n.o.b a turn, and the door opened.

33.

"Where are we?" Sarah whispered.

"I don't know."

"This is where you saw the ceremony?"

"No. This is nothing like that. Too small. Too . . . homey. The place I saw was like a cathedral."

"Well, where is that?"

"I have no idea."

The place we were in looked like a junior common room in one of the dorms, in a state of bad neglect. There were several couches with cracked and worn leather. There was a rug in the center of the room that had never been fancy, but now it was threadbare. The air was stale. I shut the door behind us and switched on a dim lamp. Old photos covered the walls, hard to make out through thick layers of dust.

On the wall opposite us were two doors.

"I guess we try those," I said.

"I wouldn't do that," Sarah whispered.

"Why not?"

"No lock on the door, out there in the hall. Don't you think that's weird? Why wouldn't they lock their door?"

"I don't know. Maybe we just got lucky for once."

"I doubt it. The only way you'd come through that door is if you were looking for it. I think this room is the lock."

"What does that mean?"

"I'm not sure," Sarah said. "I just wouldn't go touching everything."

"Look at this," Miles said.

We turned around.

On a small end table, he'd found two statues; miniature kings standing side by side, carved out of limestone. The pedestals put them at eye level with us.

They were intricately detailed, with lined robes and faces. You got the feeling they were meant to be brothers. One looked kindly, the other cold.

"Look," Sarah said. She was next to me, pointing at a plaque on one of the pedestals. It had an inscription in foreign letters. It looked like Greek.

"Miles, do they take your Cla.s.sics degree back if you actually use it for something?"

"You mock," Miles said, "but what would you do without me?"

He leaned over the plaque and ran his finger across the raised letters.

"It's a parable," he said. He laughed. "About two brothers, sworn to guard a crossroads. Not just any crossroads. One path leads to glory beyond your wildest dreams. The other leads to . . . oh."

"What--death?"

"I wish. It's from Paradise Lost. 'To bottomless perdition, there to dwell, in adamantine chains and penal fire, who durst defy th' Omnipotent to arms.'"

"Penal fire?"

"Yeah."

"It's the crossroads between heaven and h.e.l.l?"

Miles nodded.

I looked at the far wall.

"Two doors. Two paths. How do we choose?"

Miles put his finger back on the words. "According to the parable, you can ask each brother which way to go. But there's a hitch. By law, one of the brothers must always lie. The other must always tell the truth."

"No hint on which one's which?"

Miles read the rest.

He shook his head.

"That's all it says."

"What does it matter?" Sarah whispered. "They're statues. How are we supposed to ask them anything?"

I looked at the two men. Each had one arm raised over his heart, the other down by his side. At the base of each statue was a small rectangular stone that rose slightly above the stones around it.

"Okay," I said. "We push that stone. That's how we ask. Does it say anything about chances? How many chances do we get?"

"It doesn't say."

"We should be careful."

"You're right," Miles said. He reached out and pressed the stone in front of one statue.

"Miles!" Sarah cried.

The stone sank down under his finger. We heard the clicking of chains, and then, suddenly, the statue's arm began to move. Where the forearm met the elbow, there was a joint, disguised by the grooved folds of his robes. His arm actually rotated, like the hand of a clock, toward the statue's right. He came to rest pointing toward the right-hand door across the room.

"Well, it works."

"That was stupid," Sarah snapped. "This isn't a game. Stop acting like it is. Someone could get hurt."

"We had to try. What'd you want to do, talk about it until we lost our nerve?"

"Don't be stupid," she said again, poking him in the chest with her finger.

"Okay, sorry." He rubbed his chest, then nodded at the statue. "Now we know. He wants us to go that way."

"We don't know anything," Sarah said. "Is he the brother who lies or the brother who tells the truth? Maybe he's pointing us to our death."

"Fine," Miles said. He pushed the other stone.

"c.r.a.p!" Sarah shouted.

This time, the brother statue rolled his arm in the opposite direction, toward the door on the left.

"Great! Which way do we go now, genius?"

"Miles," I said, "stop touching and start thinking. Of course they were going to point in opposite directions. One's lying, one's not."

"I knew that," he said, sounding hurt. "I don't hear you offering any brilliant ideas."

"Just give me a minute to think."

"Take your time," Miles said. "I feel really comfortable here."

I closed my eyes. This was just logic. And logic was just math.

I was good at this.

Say that Truth equals +1. And a Lie is -1. Ask the lying brother, get a negative answer. Ask the truthful brother, get a positive answer.

But we don't know which one's which . . .

Come on . . . think.

It was a magic trick: we had to turn a lie into truth. In other words: how does a negative number become a positive number? . . .

Multiply it by another negative! Two negatives equal a positive!

So if you ask the liar, you have -1. How do you throw in another negative? Do the opposite of what he says! If he says go left, you go right! -1 times -1 equals +1.

But how do you know you're talking to the liar??

I mean, if you ask the truthful brother, then you're multiplying -1 times +1. You're back to the wrong answer.

s.h.i.t!

So the question is: How do you make sure that second negative is in the equation?

Come on . . .

I felt my brain stretching, groaning . . .

Almost there . . .

"I got it," I said.

Miles and Sarah stared at me.

"We ask either statue what his brother would say, and then we do the opposite."

"What?"

"Huh?"

"Think it through. We don't know who is who. So if you ask the liar what his brother would say, his brother would tell us the truth, but the liar would lie about his brother's answer. So we do the opposite!"

1 x -1 x -1 = +1!

"Or, say we ask the truth-teller. His brother would lie, and he'd truthfully tell us which way his brother recommended. So again, we do the opposite."