The girl moved into the house next door to mine so suddenly, I didn't even know she'd arrived: one day she wasn't there, and the next she was.

It was unusual that I had missed her appearance. I was seventeen at the time, going through all the usual teenage angst, and I would spend large swathes of time staring out of my window at the street outside.

I was failing school, and my teachers all told me I daydreamed too much, but I couldn't help staring out of my window, not when everything out there was so much more fascinating. I watched the same patch of grass for hours: I became closely acquainted with every piece of litter, was on a first-name basis with the squeaky gate at the end of the path, and by that February had almost reached second base with the wilting tree across the street and a few steps down.

Of all the months that year, February was by far the worst. Perhaps that was why I spent so much time trying to escape by watching the world outside. It was a surprisingly wet February - it rained almost every day, an uncomfortable sideways drizzle that somehow penetrated every pore of your skin, and meant that despite the bitter cold, snow was off the table.

So ultimately, the majority of my February was spent watching the rain christen the potholes in the tarmac and wishing I was anywhere else. I didn't go to school much. Sometimes my sister would make me go, threatening eviction or the police, but even then I'd trudge somewhere else and sit in the rain and think about things.

It was one of these days that I met the girl. I walked to the park down the road, no umbrella or raincoat, letting the drizzle frizz up my hair and collect in the palms of my hands. The park was unsurprisingly empty. I perched on the edge of a gum-stained bench, the water soaking through my jeans.

Tipping my head back, I looked up at the sky. It was the colour of an old photograph, a faded sepia, curling and flaking at the edges. Someone, somewhere, was smoking; I could smell the faint hint of cigarette smoke, and I let it catch in my throat, acrid and sour.

The rain was dripping in my eyes, so I closed them, sitting perfectly still, barely even breathing. I sat like that a lot. When I opened my eyes again, she was there.

Not three metres away from where I sat stood a girl. She had no umbrella either, and her light blonde hair was in wild curls around her face. What struck me the most about her, however, was her skin: it was blue-ish and thin as paper.

"You weren't there a second ago," I said.

"You weren't looking." She smiled. Her teeth were white and slightly crooked.

I didn't reply. She didn't say anything else, just stood there and looked at me. Her gaze was unnerving - pale and piercing. She sat down next to me, stiff and delicate, like an old black-and-white silent movie. It surprised me that she made any sound when she spoke. She carried on looking at me, flickering slightly.

"What do you want?" I said at last, a little rudely.

"You live opposite to me."

This, I thought odd. "No, you don't," I said. "Nobody lives opposite to me. That house is empty."

"Not anymore." She smiled again. I didn't like her smile, I decided. Something about it was wrong, like when you go into a familiar room and something has been moved but you don't know what's different. Her smile had that same disconcerting feeling of wrongness.

"You've moved there?" I asked, more out of politeness than real curiosity. Secretly, I wanted her to go away. I liked to be by myself more than with other people, especially not strange girls that talked funny and mysteriously appeared places.

"Yes. It's a lovely house."

"It is?" The house was horrible, I thought. Out of place in our neighbourhood of red-bricked, red-roofed terraces, it was built of a once-cream stone, now dirty and flaking, surrounded by a tangled maze of a garden, and it always looked seconds away from falling apart. No one had lived there for years, I had thought.

"I think so. It's charming." She stood up again. "I don't suppose you'd like to see it?"

"Oh, I don't know -," I started, and then cut myself off. The last thing I wanted to do was go inside this strange, displaced girl's house, but at the same time, I knew how isolating our town was. She was probably just lonely. "Alright, sure."

She smiled. I shivered. "Fantastic," she said.

I stood up and followed her towards the gate. As we walked, the grass squeaked and crunched under my feet. Under hers, however, it was silent, as if she had no mass, as if she glided across the wet earth. I suppose that should have been my first indication that something wasn't right, but I didn't think anything of it. I never thought much about the practicalities of things, as I suppose is evident from me following a random girl back to her house. I preferred big ideas and daydreams.

"How did you know I lived opposite to you? I haven't been out in days." This was true.

"I saw you, in your window." Creepy. "You spend a lot of time there. I wondered what you were thinking about."

I shrugged, not about to reveal my private thoughts to a girl I'd just met. "A lot of things."

"I can tell. It surprised me. No one ever thinks anymore." She sounded sad, wistful. All of a sudden, I felt real curiosity dig its fingernails into me, replacing the soulless apathy in which I had been marinating for as long as I could remember.

"Well, I do. I don't do much else."

We walked in silence for a few minutes. I liked to be in silence. It was comforting. I was glad she didn't try to make conversation.

She stopped outside her house. I glanced over my shoulder, checking my sister's car wasn't still in the drive - good, it wasn't. She must have already left for work. "Do you live here on your own?" I asked, as she reached into her pocket for the key.

"Yes."

"How old are you?"

"Eighteen."

"Aren't you in school?"

"Aren't you?"

Touche, I supposed. I elected not to respond. She opened the door with her paper-thin hands and long piano-player's fingers. Inside, the hallway was dark, and she made no move to switch on the light. All of a sudden, I wasn't sure about going in - but I could feel the rain getting heavier, and I couldn't bear the thought of going back to my crappy bedroom and zoning out for another day, so I cautiously stepped across the threshold.

Then she slammed the door.

I jumped a little, blindfolded by the sudden inky darkness. As my eyes adjusted, I could see her face, glowing slightly in the blackness. "Do you want me to turn on the light…?" I asked awkwardly.

She didn't reply. A long minute passed. Then she leant over and flicked a switch. I let out a shaky breath when the overhead light stuttered to life. "Come through to the kitchen," she said, as if it had never happened.

Mystified, I followed her, palms slightly raised in defense. The way my day was going, I wouldn't be surprised if someone was waiting in the shadows to tackle me.

"Would you like a drink?" she asked, pausing in the doorway.

"Only if you've got something strong," I said, pulling at a damp thread on my jumper. My clothes clung to me uncomfortably, wet and humid, and everything felt clammy and sticky.

She surprised me by opening a drawer and pulling out a small flask of something unidentified. She passed it to me. I unscrewed the cap and sniffed it covertly - I wasn't really actually a big drinker, and whatever this was smelt bitter and foul. I took a small sip, more for show, and passed it back to her, coughing slightly as I swallowed.

She tipped it to her lips and drank deeply. For some reason, the hairs on the back of my fingers and neck and back stood up and prickled dangerously. She placed the flask back down, seemingly not out of breath at all, and said "Would you like to come upstairs?"

I looked around properly. It was surprisingly nice inside actually - a little dingy and dark for my taste, but I could see the potential in the high ceilings and spacious rooms. It wasn't half as rundown as I was expecting, and certainly not as messy as you would think of someone who'd just moved in. The kitchen was admittedly rather sparsely furnished - I couldn't see anywhere to sit, for example - but it wasn't unattractive. I supposed I did want to see if the rest of the house was the same, so I nodded slowly. "Okay, sure."

She breezed past me without a sound, and led the way up a wide, rather crooked staircase. On the landing, there was a big window, framed by smooth dark brown wood, weathered and worn like it had just washed up there. Outside, the world seemed to be waiting on a drawn-out inhale, stuck in the pause between seconds. Nobody was there, or if they were they weren't moving. Everything seemed papery and thin, like it could tear or catch alight any second, and a sudden burst of fear gripped me.

I turned away from the outside world, towards the strange girl. Everything up here smelt musty and unused. The carpet, probably - it was thick pile, full of dust and god-knows-what - my feet sank into it, although hers didn't seem to leave any marks, catlike and quiet.

"Here," she said, turning into the first doorway on the left. It was a bedroom. The whole room was totally plain, the colour of an unused piece of paper. A white-covered bed that looked as if it hadn't been slept in was along one wall, and thin white curtains were drawn across the window.

I stepped further into the room, looking around. Again, it had potential - the ceiling sloped beautifully - but no character. The only thing in the room that looked like it belonged to an actual human being was a desk pushed up against the other wall. It was an enormous, arthritic, hunched-over piece of furniture made of dark brown wood, illuminated by a flickering golden lamp. Its surface was covered with sprawling papers, notebooks and pages, all covered in lines and symbols I couldn't make out. One lonely pencil slipped from a sheet of paper as I watched it, and rolled across the desk, toppling to the floor.

Lining the front of the desk were drawers, shut with grinning silver handles. One was cracked open; inside, I could glimpse yellowed papers or cards, stacked up and tied with a flash of red ribbon. Seeing me looking, she started forward and slammed it closed.

"What -" I began, startled terribly by the sudden noise. Everything in the house and everything about the girl was so awfully silent that any noise seemed out of place and just wrong.

"Sorry," she said. "Some things just aren't meant to be seen."

Embarrassed, I looked away.

Then the sky burst open.

Outside the window, everything lit up like a camera flash, so bright I squeezed my eyes closed, completely dazzled and disoriented. A clap of thunder sounded, roaring like some kind of wild animal, reverberating through my body and matching the beating of my heart. Breathing hard, I opened my eyes as the noise died away, blinking away the bright spots that danced in my retinas still.

She was gone.