Mr. Crepsley wasn't surprised that Murlough had been watching the hotel - he'd half expected it - but was stunned that I'd gone back to the square.

"What were you thinking?" he snapped.

"You didn't warn me to stay away," I replied. "I did not think I needed to."

He groaned. "What could have possessed you to return?"

I decided it was time to tell him about Debbie. He listened wordlessly as I explained.

"A girlfriend," he said at the end, shaking his head in wonder. "Why did you think I would disapprove? There is no reason you should not befriend a girl. Even full vampires sometimes fall in love with humans. It is complicated, and not to be recommended, but there is nothing wrong with it."

"You're not angry?" I asked.

"Why should I be? Matters of your heart are no concern of mine. You acted properly: you made no promises you could not keep, and you remained aware of the fact that it could only be temporary. All that worries me about your friendship with this girl is how it ties in with the vampaneze."

"You think Murlough will go after her?"

"I doubt it," he said. "I think he will stay clear of the square. Now that we know he has been there, he will expect us to check on the area in the future. However, you should be careful. Do not go to see her when it is dark. Enter by the back door. Keep away from the windows."

"It's okay for me to keep meeting her?" I asked.

"Yes." He smiled. "I know you think I often spoil the fun, but I would never intentionally make you feel miserable."

I smiled back gratefully.

"And Evra?" I asked. "What will happen to him?"

Mr. Crepsley's smile faded. "I am not sure." He thought about it for a couple of minutes. "You truly refused to swap my life for his?" He sounded as if he thought I might be making it up to impress him.

"Honestly," I said.

"But why?"

I shrugged. "We said we'd trust each other, remember?"

Mr. Crepsley turned aside and coughed into his fist. When he faced me again, he looked ashamed of himself. "I have gravely underestimated you, Darren," he said. "I will not do so again. I made a wiser choice than I realized when I chose you to serve as my assistant. I feel honored to have you by my side."

The compliment made me feel awkward - I wasn't used to the vampire saying nice things - so I grimaced and tried to make nothing out of it.

"What about Evra?" I asked again.

"We shall do what we can to rescue him," Mr. Crepsley said. "It is unfortunate that you refused to swap me for him: had we known Murlough would make the offer, we could have laid a trap. Now that you have shown loyalty toward me, he will not offer again. Our best chance to beat him has slipped away.

"But there is hope yet," he said. "Today is the twenty-third. We know that Evra will not be killed before the twenty-fifth."

"Unless Murlough changes his mind," I said.

"Unlikely. The vampaneze are not renowned for being indecisive. If he said he would not kill Evra until Christmas Day, that is when he will kill him. We have all tonight and tomorrow night to search for his lair."

"But he could be anywhere in the city!" I cried.

"I disagree," Mr. Crepsley said. "He is not in the city - he is under it. Holed up in the tunnels. The drainpipes. The sewers. Hiding from the sun, free to move about as he wishes."

"You can't know that for sure," I said. "He might have only been down there today in order to follow me."

"If he was," Mr. Crepsley said, "we are sunk. But if he has made his base down there, we stand a chance. Space is not so plentiful beneath the ground. Noises are easier to detect. It will not be easy, but there is hope. Last night, we did not even have that.

"If all else fails," he added, "and we end up empty-handed..." His face hardened. "I will call to our murderous cousin and offer him the deal which you yourself put to him earlier."

"You mean...?"

"Yes," he said darkly. "If we do not find Evra in time, I will trade my life for his."

There was more space beneath the ground than Mr. Crepsley had predicted. It was an endless, twisting maze down there. The pipes seemed to go everywhere, like they were thrown down at random. Some were big enough to stand in, others barely large enough to crawl through. Many of them were in use, half full of streams of water and waste. Others were old and dried-up and cracked.

The stench was terrible. One thing was certain: we might happen to hear or glimpse Murlough or Evra, but we'd definitely never be able to sniff them out!

The place was awash with rats and spiders and insects. But I soon discovered that if you ignored them, they generally ignored you back.

"I do not understand why they need so many tunnels," Mr. Crepsley said grimly, after several hours of fruitless searching. We seemed to have walked halfway across the city, but when he stuck his head above ground to check our position, he discovered we'd gone less than three-quarters of a mile.

"I guess different tunnels were made at different times," I said. My dad used to work for a construction company and had explained a little about underground systems to me. "They wear out in places, eventually, and it's usually easier to dig new shafts than go back and patch up the old ones."

"What a waste," Mr. Crepsley grumbled disdainfully. "You could fit a small town into the space these damned pipes are taking up." He looked around. "There seem to be more holes than concrete," he said. "I am surprised the city has not fallen in upon itself."

After a while, Mr. Crepsley stopped and cursed.

"Do you want to stop?" I asked.

"No," he sighed. "We shall continue. It is better to search than sit back and wait. At least this way we are exerting some sort of control over our destiny."

We used torches in the tunnels. We needed some kind of light: even vampires can't see in total darkness. The beams increased the chances of Murlough's spotting us before we spotted him, but that was a risk we had to take.

"There's no way of hunting him down telepathically, is there?" I asked as we paused for a break. All this crawling and crouching was exhausting. "Couldn't you search for his thoughts?"

The vampire shook his head. "I have no connection with Murlough," he said. "Tuning into a person's mental signals requires radarlike emissions on both sides." He held up his two index fingers about a foot apart. "Say this is me." He wiggled his right finger. "This is Mr. Tall." He wiggled the left. "Many years ago, we learned to recognize each other's mental waves. Now, if I want to find Mr. Tall, I emit a radar-like series of waves." He bent his right finger up and down. "When these signals connect with Hibernius, part of his mind automatically signals back, even if his conscious mind remains unaware of it."

"You mean you could find him even if he didn't want to be found?"

Mr. Crepsley nodded. "That is why most people refuse to share their wave identity. You should only reveal it to one you truly trust. Less than ten people on Earth can find me that way, or I them." He smiled thinly. "Needless to say, none of those ten is a vampaneze."

I wasn't sure I understood completely about mental waves, but I'd taken in enough information to know Mr. Crepsley couldn't use it to find Evra.

One more hope struck from the list.

But the conversation made me start thinking. I was sure there must be some way of bettering the odds. Mr. Crepsley's plan - to roam the tunnels and pray we fell upon the vampaneze - was weak. Was there nothing else we could do? No way to prepare a trap and lure Murlough into it?

I focused my immediate thoughts on the search - if we stumbled upon the crazy vampaneze, I didn't want to be caught with my head in the clouds - but devoted the rest to serious thinking.

Something the vampaneze had said was poking away at the back of my brain, but I couldn't put my finger on it. I went back over everything he'd said. We'd talked about Evra and Mr. Crepsley and Debbie and making a deal and...

Debbie.

He'd teased me about her, said he was going to kill her and drink from her. At the time I didn't think it was a serious threat, but the more I thought about it, the more I began to wonder how much he really was interested in her.

He would be hungry, down here in the depths. He was used to feeding regularly. We'd ruined his schedule. He'd said he was looking forward to drinking Evra's blood, but was he? Vampires couldn't drink from snakes and I was willing to bet vampaneze couldn't, either. Maybe Evra's blood would prove to be undrinkable. Maybe Murlough would only be able to kill the snake-boy on Christmas Day, not drink from him as he planned. He'd commented a couple of times on how tasty Debbie looked. Was that a clue that Evra didn't look tasty?

As the time ticked by, thoughts turned over in my head. I didn't say anything when Mr. Crepsley told me we should return to the surface (he had a natural built-in clock), in case Murlough was shadowing us and listening to our every word. I kept quiet as we climbed out of the tunnel and trudged through the streets and then went up to the roofs again. I held my tongue as we snuck through our hotel window and sank into chairs, tired, miserable, and gloomy.

But then, hesitantly, I coughed to attract the vampire's attention. "I think I have a plan," I said, and slowly spelled it out for him.