ONE DUSK I awoke with a feeling of absolute comfort. As I stared up at a red, darkening sky, I tried putting my finger on why I felt so good. Then I realized - the itching had stopped. I lay still a few minutes, afraid it would return if I moved, but when I finally got to my feet, there wasn't the slightest prickling sensation. Grinning, I headed for a small pond we'd camped by, to wet my throat.

I lowered my face into the cool, clear water of the pond and drank deeply. As I was rising, I noticed an unfamiliar face in the reflecting surface of the water - a long-haired, bearded man. It was directly in front of me, which meant he must be standing right behind me - but I hadn't heard anyone approach.

Swivelling swiftly, my hand shot to the sword which I'd brought from Vampire Mountain. I had it halfway out of its scabbard before stopping, confused.

There was no one there.

I looked around for the shabby, bearded man, but he was nowhere to be seen. There were no nearby trees or rocks he could have ducked behind, and not even a vampire could have moved quickly enough to disappear so swiftly.

I turned back towards the pond and looked into the water again. There he was! As clear and hairy as before, scowling up at me.

I gave a yelp and jumped back from the water's edge. Was the bearded man in the pond? If so, how was he breathing?

Stepping forward, I locked gazes with the hairy man - he looked like a caveman - for the third time and smiled. He smiled back. "Hello," I said. His lips moved when mine did, but silently. "My name's Darren Shan." Again his lips moved in time with mine. I was getting annoyed - was he mocking me? - when realization struck - it was me!

I could see my eyes and the shape of my mouth now that I looked closely, and the small triangular scar just above my right eye, which had become as much a part of me as my nose or ears. It was my face, no doubt about that - but where had all the hair come from?

I felt around my chin and discovered a thick bushy beard. Running my right hand over my head - which should have been smooth - I was stunned to feel long, thick locks of hair. My thumb, which stuck out at an angle, caught in several of the strands, and I winced as I tugged it free, pulling some hair out with it.

What in Khledon Lurt's name had happened to me?

I checked further. Ripping off my T-shirt revealed a chest and stomach covered in hair. Huge balls of hair had also formed under my armpits and over my shoulders. I was hairy all over!

"Charna's guts!" I roared, then ran to wake my friends.

Mr. Crepsley and Harkat were breaking camp when I rushed up, panting and shouting. The vampire took one look at my hairy figure, whipped out a knife and roared at me to stop. Harkat stepped up beside him, a grim expression on his face. As I halted, gasping for breath, I saw they didn't recognize me. Raising my hands to show they were empty, I croaked, "Don't... attack! It's... me!"

Mr. Crepsley's eyes widened. "Darren!"

"It can't be," Harkat growled. "This is an impostor."

"No!" I moaned. "I woke up, went to the pond to drink, and found... found..." I shook my hairy arms at them.

Mr. Crepsley stepped forward, sheathed his knife, and studied my face incredulously. Then he groaned. "The purge!" he muttered.

"The what?" I shouted.

"Sit down, Darren," Mr. Crepsley said seriously. "We have a lot of talking to do. Harkat - go fill our canteens and fix a new fire."

When Mr. Crepsley had gathered his thoughts, he explained to Harkat and me what was happening. "You know that half-vampires become full-vampires when more vampire blood is pumped into them. What we have never discussed - since I did not anticipate it so soon - is the other way in which one's blood can turn.

"Basically, if one remains a half-vampire for an extremely long period of time - the average is forty years - one's vampire cells eventually attack the human cells and convert them, resulting in full-vampirism. We call this the purge."

"You mean I've become a full-vampire?" I asked quietly, both intrigued and frightened by the notion. Intrigued because it would mean extra strength, the ability to flit and communicate telepathically. Frightened because it would also mean a total retreat from daylight and the world of humanity.

"Not yet," Mr. Crepsley said. "The hair is simply the first stage. We shall shave it off presently, and though it will grow back, it will stop after a month or so. You will undergo other changes during that time - you will grow, and experience headaches and sharp bursts of energy - but these too will cease. At the end of the changes, your vampiric blood may have replaced your human blood entirely, but it probably will not, and you will return to normal - for a few months or a couple of years. But sometime within the next few years, your blood will turn completely. You have entered the final stages of half-vampirism. There is no turning back."

We spent most of the rest of the night discussing the purge. Mr. Crepsley said it was rare for a half-vampire to undergo the purge after less than twenty years, but it was probably linked to when I'd become a Vampire Prince - more vampiric blood had been added to my veins during the ceremony, and that must have speeded up the process.

I recalled Seba studying me in the tunnels of Vampire Mountain, and told Mr. Crepsley about it. "He must have known about the purge," I said. "Why didn't he warn me?"

"It was not his place," Mr. Crepsley said. "As your mentor, I am responsible for informing you. I am sure he would have told me about it, so that I could have sat down with you and explained it, but there was no time - Mr. Tiny arrived and we had to leave the Mountain."

"You said Darren would grow during... the purge," Harkat said. "How much?"

"There is no telling," Mr. Crepsley said. "Potentially, he could mature to adulthood in the space of a few months - but that is unlikely. He shall age a few years, but probably no more."

"You mean I'll finally hit my teens?" I asked.

"I would imagine so."

I thought about that for a while, then grinned. "Cool!"

But the purge was far from cool - it was a curse! Shaving off all the hair was bad enough - Mr. Crepsley used a long, sharp blade, which scraped my skin raw - but the changes my body was undergoing were much worse. Bones were lengthening and fusing. My nails and teeth grew - I had to bite my nails and grind my teeth together while I walked at night to keep them in shape - and my feet and hands got longer. Within weeks I was five centimetres taller, aching all over from growth pains.

My senses were in a state of disarray. Slight sounds were magnified - the snapping of a twig was like a house collapsing. The dullest of smells set my nose tingling. My sense of taste deserted me completely. Everything tasted like cardboard. I began to understand what life must be like for Harkat and made a resolution never to tease him about his lack of taste buds again.

Even dim lights were blinding to my ultra-sensitive eye. The moon was like a fierce spotlight in the sky, and if I opened my eyes during the day, I might as well have been sticking two fiery pins into them - the inside of my head would flare with a metallic pain.

"Is this what sunlight is like for full-vampires?" I asked Mr. Crepsley one day, as I shivered beneath a thick blanket, eyes shut tight against the painful rays of the sun.

"Yes," he said. "That is why we avoid even short periods of exposure to daylight. The pain of sunburn is not especially great - not for the first ten or fifteen minutes - but the glare of the sun is instantly unbearable."

I suffered with immense headaches during the purge, a result of my out-of-control senses. There were times when I thought my head was going to explode, and I'd weep helplessly from the pain.

Mr. Crepsley helped me fight the dizzying effects. He bound light strips of cloth across my eyes - I could still see pretty well - and stuffed balls of grass into my ears and up my nostrils. That was uncomfortable, and I felt ridiculous - Harkat's howls of laughter didn't help - but the headaches lessened.

Another side-effect was a fierce surge of energy. I felt as if I was operating on batteries. I had to run ahead of Mr. Crepsley and Harkat at night, then double back to meet them, just to tire myself out. I exercised like crazy every time we stopped - push-ups, pull-ups, sit-ups - and usually woke long before Mr. Crepsley, unable to sleep more than a couple of hours at a time. I climbed trees and cliffs, and swam across rivers and lakes, all in an effort to use up my unnatural store of energy. I'd have wrestled an elephant if I'd found one!

Finally, after six weeks, the turmoil ceased. I stopped growing. I didn't have to shave any more (though the hair on my head remained - I was no longer bald!). I removed the cloth and grass balls, and my taste returned, although patchily to begin with.

I was about seven centimetres taller than I'd been when the purge hit me, and noticeably broader. The skin on my face had hardened, giving me a slightly older appearance - I looked like a fifteen- or sixteen-year-old now.

Most importantly - I was still a half-vampire. The purge hadn't eliminated my human blood cells. The downside of that was I'd have to undergo the discomfort of the purge again in the future. On the plus side I could continue to enjoy sunlight for the time being, before having to abandon it forever in favour of the night.

Although I was keen to become a full-vampire, I'd miss the daytime world. Once my blood turned, there was no going back. I accepted that, but I'd be lying if I said I wasn't nervous. This way, I had months - perhaps a year or two - to prepare myself for the change.

I'd outgrown my clothes and shoes, so I had to stock up at a small human outpost (we were leaving civilization behind again). In an army surplus shop, I chose gear similar to my old stuff, adding a couple of purple shirts to my blue ones, and a dark green pair of trousers. As I was paying for the clothes, a tall, lean man entered. He was wearing a brown shirt, black trousers and a baseball cap. "I need supplies," he grunted at the man serving behind the counter, tossing a list at him.

"You'll need a licence for the guns," the shopkeeper said, running an eye over the scrap of paper.

"I've got one." The man was reaching into a shirt pocket when he caught sight of my hands and stiffened. I was holding my new clothes across my chest, and the scars on my fingertips - where I'd been blooded by Mr. Crepsley - were clear.

The man relaxed instantly and turned away - but I was sure he'd recognized the scars and knew what I was. Hurrying from the shop, I found Mr. Crepsley and Harkat on the edge of town and told them what had happened.

"Was he nervous?" Mr. Crepsley asked. "Did he follow when you left?"

"No. He just went stiff when he saw the marks, then acted as though he hadn't seen them. But he knew what the marks meant - I'm certain of it."

Mr. Crepsley rubbed his scar thoughtfully. "Humans who know the truth about vampire marks are uncommon, but some exist. In all probability he is an ordinary person who has simply heard tales of vampires and their fingertips."

"But he might be a vampire hunter," I said quietly.

"Vampire hunters are rare - but real." Mr. Crepsley thought it over, then decided. "We will proceed as planned, but keep our eyes open, and you or Harkat will remain on watch by day. If an attack comes, we shall be ready." He smiled tightly and touched the handle of his knife. "And waiting."