The party's not set to start until seven, but the first guests begin arriving soon after six. I'm nervous and twitchy, worrying about where their coats should go, if there's enough food and drink, if anyone's smuggled in anything they shouldn't have. But as more arrive and the laughter and buzz of voices increase, I begin to relax as I realise people are having fun.

Not everyone who comes was on the invitation list, but there's nothing I can do about that. If I turned them away, I'd sour the atmosphere. A few blow-ins have to be expected at any party.

Loch and Frank help (Leon can't make it until nine), opening the front doors and greeting newcomers while I'm showing others around the mansion. It's cool to be a guide to so many fascinated guests. I love leading them through the corridors, pointing out weapons on the walls, explaining the house's bloody history, showing them the hall of portraits and the faces of the dead.

"How come there are so many young people?" Mary asks, studying the paintings and photos.

"We're an adventuresome lot," I lie. "We don't sit around quietly, waiting to grow old. We embrace life and danger, and as a result a lot of us die young."

"They leave good looking corpses though," Reni says and giggles sweetly when I blush.

Bill-E arrives at a quarter to eight. I'm coming down the stairs when he enters, admitted by Loch.

"Hey, Bill-E, great to see you, glad you could come," Loch enthuses, offering his hand, which Bill-E predictably-and, I must admit, amusingly-tries to shake. "Sucker!"

But even Loch's teasing can't spoil the mood. Bill-E breezes past him, feathers only mildly ruffled, and makes for the nearest pile of food. Ten minutes of solid munching later, he's by my side, marching after me as I lead the latest group on a tour. By midway he's taken over-he knows much more about the house and its legends than I do and is better at telling the stories. I don't mind. It's nice to see him come out of his shell. I wish he was like this all the time.

As the night lengthens I start to feel strange. Nauseous, dizzy, the rooms and people around me appearing oddly out of focus. My breath is heavy in my ears and my stomach and chest ache if I move quickly. It's not alcohol-nobody brought booze-but maybe somebody spiked the soft drinks with a spoon of nasty powder or a pill.

"Are you OK?" Reni asks, spotting me staggering towards the kitchen.

"A bit... weird..." I gasp, having to sit on the floor a couple of metres shy of the kitchen door.

Reni squats beside me. "You don't look good," she says and feels my forehead. "You haven't been drinking, have you?" I shake my head. "Drugs?" Her voice is hard.

"Not... that I know... about," I wheeze. "I was going... to the kitchen... to check. Think somebody... might have spiked... the drinks."

"They'd better bloody not," Reni growls, surging to her feet. "I'll have them arrested if they have! You wait here." She storms off to investigate. Five or ten minutes later-hard to keep track of time, my head's throbbing so much-she returns, calmer. "Everyone else is fine. I don't think the drinks have been tampered with."

"Maybe I'm just sick," I mutter.

"That's what it looks like," she says, then grabs my arms and hauls me to my feet. "Let's get you outside. Fresh air will do you a world of good."

She steers me through the kitchen and out the back door, then props me against the wall and stands watch beside me as I take deep breaths and try to focus. After a few minutes my head clears a little and my stomach settles.

"Better?" Reni asks, tilting my chin up, examining my eyes.

"Good as new," I smile.

Reni leans towards me, a serious look in her eyes. I tense. Will this be our first kiss? I hope I don't mess up. How do they do it in the movies-tongue or just lips? But at the last moment her expression crinkles and she kisses me quickly on the nose instead of the mouth.

"Come on, Romeo," she laughs, taking my hands. "It's too cold out here for monkey business."

"What about inside?" I murmur, smiling at myself for getting the line out without stammering.

"Maybe later," Reni grins and heads back in. I follow in high spirits, feeling much better than I did a few minutes ago. It's only when we reach the kitchen door that I stop and feel a stab of real panic.

The light's been switched off inside the kitchen. I can see the reflection of the sky in the dark glass of the door. Letting go of Reni's hand, turning slowly, I look up at the cloudless heavens and fix my sight on the moon-which is round and fat, dangerously near to full.

Locked inside Dervish's study. Breath coming quickly, raggedly. Trembling wildly. Remembering the night Bill-E changed, the beast he became. Dervish had to cage him up to protect people from him. He would have killed otherwise.

Am I turning into a werewolf?

I don't know. The sickness and dizziness are still there, but they might be more a product of fear than anything else. Maybe it's just worry that's turned me white as a ghost and left me ready to throw up, shaking like a human maraca.

I focus on my hands, willing them steady. After a while they obey me. Then I force myself to breathe normally, evenly. When I feel like I'm in control, I study my reflection in a small hand mirror, looking for telltale signs around the eyes and lips-that's where the marks show first.

Nothing. The same lines and creases. Eyes a bit wilder than normal-which is understandable-but mine. Not clouded over or animalistic.

I wish Dervish was here. I consider calling his mobile. He isn't that far away. The speed he drives, he could be here in a couple of hours. I dig my phone out of my pocket, scroll down to his number, start to bring my thumb down over the dial button... then stop.

"I'm not turning," I grunt, angry at myself for being so scared. "It's after ten." I check my watch. "Hell, nearly eleven. The moon's at the height of its powers. If I was going to change, it would have happened by now."

But maybe it's the start, a voice within me whispers, a voice I last heard in Slawter many months earlier-the voice of magic. Nobody changes overnight. It's a gradual process, spread out over a few months. This could be the beginning of the end.

"Maybe," I agree, refusing to panic. "But I'm not going to turn savage tonight. Nobody has anything to fear from me. So there's no point dragging Dervish back."

But if it's the change... If your time as a human is limited...

"All the more reason to party hard while I can," I laugh viciously, then make myself go downstairs, smile and act like everybody else-normal.

Midnight comes and goes. So do most of the guests, walking or cycling home, a few collected by their parents. By half past, only those who are sleeping over remain-Loch, Frank, Leon, Charlie, Robbie, Bill-E, Reni, Mary and a few others who've begged a bed for the night. (OK, I lied to Dervish about only boys staying, but what he doesn't know can't hurt him, right?)

"Do you want me to show you where you'll be sleeping?" I ask, eager to wind the party down, still feeling sick.

"The hell with sleep," Frank laughs. "Time for spin-the-bottle!"

While there are good-natured groans, nobody objects, so five minutes later we're all in the largest of the party rooms, sitting in a nervous circle around an empty bottle. Lots of giggles, nervous looks, licking of lips. I do a quick head count-nine boys, four girls.

"How are we going to work this?" I ask Frank.

"We each take a turn spinning," he says, rubbing his hands together eagerly. "When it points to a member of the opposite sex-hoobah!"

"But there's more of us than them," I object.

"So?" he frowns.

"Well... I mean... at least two of them are going to have to kiss more than one guy." Worried about Reni kissing anyone other than me.

Frank laughs. "That's how it works, moron. We all get plenty of action."

"Only simple kisses," Mary interjects. "No groping or tongues, not unless both want to. Clear?"

"Of course, of course!" Frank says quickly, leering.

"We mean it," Reni says. "If one of you breaks the rules, that's it, end of game, you all miss out."

"OK," Frank sighs, rolling his eyes. "We get the message. Now, who first?"

"It's Grubbs's party," Loch says.

"That's OK," I cough, getting cold feet. "I think Bill-E should have first shot."

"I second the motion," Bill-E laughs, more at ease than I've seen him in a long time. He grabs the bottle and spins it madly. It turns... turns... turns...like it's never going to stop. But finally it does-and it's pointing at Reni.

Bill-E grins. "Sorry, amigo, but the bottle decides."

I feel my temper rise as Bill-E and Reni meet in the middle of the circle to a series of whistles and crude remarks. The bile that's been threatening to bubble over all night forces its way up my throat. But then Reni pecks him on the lips and they both sit down. I relax, swallow the vomit and grin greenly.

The game continues. Great laughs when one of the boys spins and it ends up pointing to another boy. Lewd giggles when that happens to the girls. Most of the kisses are like the first, quick pecks. But a few are stronger, where the pair are attracted to each other-Robbie and Mary, Leon and Nina Duffy.

I get to kiss Mary twice, Nina three times ("This is getting serious," she says jokingly), before Reni finally spins and the bottle ends up pointing at me.

"Whoo-hoo!" Frank chortles.

"Touchdown!" Charlie cries.

"Easy, tiger," Loch grunts, smiling tightly.

Reni and I stand and walk towards each other. Reni nudges the bottle out of the way with her left foot. We smile shakily. Then kiss.

Her lips are drier than I thought they'd be, but nice. My hands slide around her back and I lock my fingers together, careful not to hug too hard in case I crack her ribs. The kiss continues. Her lips move and mine follow-this is easier than I imagined. I don't know why I was so nervous before. I could get used to this very quickly!

Lots of cheers and whistles. I drown them out, eyes closed, feeling so happy I could burst. A warm fire grows within me, burning away the feeling of sickness, spreading rapidly through my body, squeezing out of my pores like steam. I lose myself in the hot, hypnotic kiss, unaware of anything else.

Then gasps of amazement wreck the moment.

"What the-?"

"How the hell-?"

"Oh my god!"

My right eye opens an angry fraction-what's everybody getting so worked up about? Then I spot it. The bottle, spinning again, but not on the ground-about a metre above the floor, suspended in mid-air, floating upwards as it spins.

The bottle rises smoothly. Everyone (with a single exception) is on their feet, backing away, alarmed. Reni realises something's wrong. She breaks off the kiss, takes a step back, sees the bottle. Her expression freezes.

Bill-E's the only one not moving. He's staring at the bottle intently. I think for a second that he's controlling it, using one of Dervish's spells. I huff myself up to roar at him. But then I catch the alarm in his eyes and realise he's trying to stop it. I'm the one making it rise.

The bottle reaches a point about half a metre above my head, then levels out. It's spinning faster than ever, making a small whirring sound.

"What's happening?" Robbie shouts. "Grubbs, are you doing this?"

I don't answer. My gaze is on the bottle. Although it's spinning too quickly for the eye to follow, I find that I can slow the action down. The world seems to go into slow-motion around me. People's mouths move infinitely slowly. Words reach me as though dragged through a pipe from a long way away.

"Grrruuuubbbssssss! Whaaaaattttt'sss... goooiiiinnngggg oooonnnn?"

The bottle explodes and the world speeds up again. Shards of glass shoot at me, Reni, everybody in the room, at our faces and eyes. Instinctively I bark a word of magic. I don't know what the word is or where it comes from. But it freezes the shards in place. They hang in mid-air, dozens of tiny pieces of glass, pointing at us like a flight of mini arrows.

"No way!" somebody shouts, more excited than afraid. My friends start lowering the hands which they'd instinctively raised to protect themselves.

Bill-E stares at the bits of glass-then at me. His eyebrows are furrowed. He knows this is magic but he can't understand how I'm doing it. He saw me do more than this in Slawter, but that enclosed area was crackling with magical energy. Many of us could perform amazing feats there. In the real, normal world, he thought-like Dervish-that I had all the magical ability of a duck.

"Grubbs," Reni says uncertainly, touching my right elbow. "Are you OK?"

"Yes," I whisper.

"Do you know what's happening?" Scared, looking for reassurance, gazing at the shard nearest her face, worried it might shoot forward again.

"Yes," I smile. Without knowing how I'm doing any of this, I wave a hand at the glass and several pieces turn into flower petals, which drop slowly, beautifully to the floor. I wave my other hand and more shards turns into butterflies. They flap away, zoning in on the light overhead. One last wave and the rest of the glass is transformed, a mixture of butterflies and flowers.

I grab one of the falling petals and present it to Reni. "For you, my lady."

Then everybody's cheering, clapping my back, grabbing for petals and butterflies, demanding to know how the trick was performed.

Only Bill-E knows there was no trick. Only he realises this was real magic. And only he can possibly understand and share in my sense of bewilderment and gut-stabbing fear.

Later. Everyone but Bill-E and me has gone to bed. I'm at the door of my room, still holding a petal. Bill-E's facing me, eyes steady and serious. "How'd you do it?"

"Dervish has been teaching me."

Bill-E shakes his head. "Bull. Dervish told me you don't want to learn magic. He's cool with that. But even if he was teaching you, that's way beyond anything I've ever seen him do. Apart from in Slawter." He looks around nervously. "Are demons breaking through? Did you tap into their power?"

"No. We're safe here. Demons can't cross in Carcery Vale."

"Then how did you do it?" he presses. "Where did the magic come from?"

I shake my head miserably. "Forget about it. This doesn't concern you."

"I might be able to help if I-"

"I told you it's none of your business!" Bill-E looks hurt and I feel sorry immediately. "It's no big deal," I lie. "This has been building up for a long time. I haven't spoken with Dervish about it, but after tonight I guess I'll have to."

"This isn't the first time it happened?" Bill-E asks.

"There have been signs but nothing this obvious."

"Do you think..." He can hardly bring himself to say it. "Do you think you might be a magician?"

"No. Dervish would know if I was. But maybe I've got more potential than we thought. I might be a latent mage. If so, Dervish will know what to do."

Bill-E nods, starts to leave, looks back. "You won't be able to turn away from it anymore," he says softly. "Magic, I mean. You'll have to learn now, so you can control it. If you hadn't been able to stop that glass tonight... if you hadn't turned it into butterflies and flowers..."

"I know," I sigh.

"You'll really tell Dervish? You won't try to keep it a secret?"

"I'll tell him. I'm not a fool. I know what magic can do if it isn't properly channelled. I don't want to hurt anyone."

Bill-E smiles, says goodnight and leaves.

I slip into my bedroom, lie on top of the covers fully clothed and stare at the ceiling, listening to my heart pound and my blood swoosh through my body, trying to make sense of whatever the hell is happening inside me.

Later. Slowly coming awake. Sluggishly realising I must have fallen asleep on top of the bed. Then I click to the fact I'm not on the bed anymore. I'm standing by the round stained-glass window in my bedroom, listening to howls outside. No, not outside-in here!

My head whips round in panic. Fully awake now. I can't see anything in the room but I can hear the howls of a werewolf! Where is it? It must be close. It's so loud. Where...?

With a jolt, I realise he's in the glass in front of me. At least, his reflection is.

My face is darker than earlier. A wicked glint to my eyes. Lips pulled back over my teeth. Raising a hand, I see that my fingers are curling inwards, claw-like. I start to howl again, stepping into the coloured rays of the moon.

I stop. Focusing on my reflection, I feel the same warmth that I felt when I was kissing Reni, just before the bottle started to rise. I study my face, the sharp lines, the wild eyes. Directing the warmth towards it, I wish the mask away, wanting my normal face back, telling this vision of a man-wolf to go.

And it does. Even though it shouldn't, my skin resumes its ordinary shape and colour. My lips droop back down over my teeth. My fingers unclench. The howl dies in my throat and becomes a dry cough.

Moments later I'm me again, standing by the window, bathed by the tinted light of a moon which for some reason is no longer affecting me. The warmth is still there. I hold on to it like a security blanket, take it to bed with me and sustain it, keeping it alive through the rest of the long, weary night, too terrified to close my eyes, afraid of what I might turn into if I drop my guard and give myself over to unprotected sleep.