This week has been disturbing and unusual, I need to write things down. Maybe I shouldn't have come back to the library, but it's clear I've somehow got myself involved in something that's not going away.

Last Saturday morning, I was wandering around this same library with no plans. I love the Central Library, its high wooden shelves and smell of knowledge: it's useful for work (local magazine journalist), and it's great for useless things which are just interesting in themselves.

Last week, I found the Mythology section, tucked away in a corner of Reference I hadn't found before: lots of weighty old tomes of collected folklore and folktales, and all sorts of other weirdness. I was running my hand carefully along the cracked leather of some spines when my fingers snagged on a small volume tucked between two much bigger ones. I tugged it forward, trying to read the faded title on the worn cloth spine.

Which is why I didn't see the librarian. Possibly.

"Come this way, honourable scholar."

I ignored the whisper, assuming it was one of the eccentric old-timers who always seem to be around. With a little more wiggling, I managed to get a reasonable grasp of the book.

"Bring the book, scholar," whispered the voice, less eccentrically and with a hint of impatience.

I looked round and jumped, because a little grey lady in spectacles and a prim check skirt was at my shoulder. Not a usual staff member. I checked over my other shoulder: although I'm not stupid and got good marks at uni, calling me a 'scholar' is generous. There was, of course, no-one else nearby, and she was definitely staring at me.

"Sorry. Am I in your way?"

"No, scholar, I'm addressing you." She frowned suddenly. "What on earth has happened to your skirt?"

I looked down, and saw nothing particularly wrong with the check miniskirt I was wearing. (Apart from the odd fact that the pattern was identical to her own.) I tried to look over my own shoulder, to check the back.

"You're showing your legs," sniffed the librarian, in the sort of disapproving tone only old-fashioned middle-aged women can do properly.

"Oh." I wondered what decade she lived in. "They're not that bad, are they...?"

She waved her hand. "Enough." She cast another quick, sceptical glance at my skirt (or maybe my legs), then gestured to a study carrel behind her, which I hadn't really noticed before. "Come."

*

The next fifteen minutes were bizarre. The little grey librarian sat me down and tried to get me interested in something to do with the book (still unopened in my hand): there was a lot of stuff about being chosen, which passed me by. There was something about nuns and illicit lust, which sounded a lot more promising. But it was all mainly lost in her constant silent disapproval of my skirt length.

I looked away and sighed, and she disappeared. I looked for her amongst the bookshelves, but that was obviously futile.

Returning to the carrel, I saw I'd missed a call from Jules, my deputy editor, which was unusual on a weekend – they didn't like to pay me overtime. The little book had disappeared as well. I decided to leave the library, as it was being weird, and rang Jules back as I walked home.

She wanted me to fill in for a colleague at the last minute, and attend a high-society Hallowe'en dinner that evening, to take photos for the magazine's November issue; she was – unusually for Jules – almost apologetic.

*

That evening, in my best little black dress, I parked behind a cluster of expensive cars in the driveway of The Old Priory, Church Durton (a new hotel venture in an old manor house, that Jules and I had featured in the magazine back in the Summer). The hostess met me in the entrance hall and gave me carte-blanche to snap away at her guests, until they all went into dinner. They needed publicity, and a society feature in our magazine was good for everyone.

I dutifully snapped away, and flirted discreetly with a pretty waitress in a black miniskirt who kept me supplied with canapés on the quiet.

When the guests moved into dinner, my job was done: the hostess only wanted pictures of the drinks reception. Sarah, the drinks waitress, found me alone in the entrance hall and pulled me through a door beneath the main staircase.

This was a much older part of the house. We kissed heavily, then ascended a dark corridor with various heavy wooden doors off it. The wooden floors creaked under our feet, although we tried to step lightly. Sarah went ahead, undoing her apron, looking for a room suitable for our purposes, while I took a couple of quick pictures: the old stone vaulting of the ceiling was very fine; and the timber-and-plaster walls between occasional stone columns, and the uneven wooden floor, all made for a very atmospheric effect in the gloom.

Sarah leant suggestively in an open doorway. "In here," she whispered, undoing a button or two of her blouse.

I put my camera down carefully, and let her drag me by the collar of my dress over to the bed.

My hand was edging between her thighs under her miniskirt, and hers was moving inside my dress, when there was a soft groan behind us. "Was that you?" I whispered, aroused and slightly surprised.

"No. Thought it was you."

I felt goosebumps on my neck and arms, but not from Sarah's kisses.

"I can moan if you want me to, though," she added, moving her legs further apart.

"Shh." I kept my hand on her leg but cocked my head to listen more carefully. There was a definite quiet moaning coming from nearby, but it wasn't a nice sound. "You hear that?"

Sarah nodded against my shoulder. We separated, sitting up carefully. The moaning rose in pitch and intensity until it was more like a cry. Sarah stood up, straightening her skirt, and fumbled her feet into her shoes. "Sod this."

The ethereal crying reached such a pitch that it was almost a scream, and I felt my skin prickle. I stumbled into my heels and hurried after Sarah from the room, only pausing by the door to collect my camera. In my clumsy haste, I accidentally triggered it a few times.

As we crept back to the door to the main hall, the high-pitched crying subsided into a series of sobs. We paused as the sobs became whimpers, and Sarah slipped her hand into mine. "Weird."

"Mmm. Shame we were interrupted..."

She pushed against me. "Give me a lift home...?"

The sobs rose again suddenly, then stopped abruptly. Sarah squeezed my hand, just as there was a clattering like metal on stone, which almost certainly came from where we'd just been, and then a long, sharp cry.

"Shit," she whispered into my hair. "That was in that room, wasn't it?"

"Yep."

She pushed through the door back to the main hallway. "Stuff this, I'm off."

I got us away down the drive without scratching any of the posh cars. We were both so shaken by the disembodied cries that I just dropped her in her village, and set off home myself. We didn't even swap numbers.

When I looked at them, my accidental photos showed the indistinct figure of a nun in distress, standing over the bed we'd been using.

**

As I'd half-expected, the little grey librarian was waiting for me this morning. Feeling defiant, I've deliberately worn a short corduroy pinafore dress under an old-school woolly cardigan; to my dismay, she was wearing a prim skirt of the exact same shade of blue as my dress, and practically the same cardigan (although it didn't look retro on her). Didn't stop her casting another disapproving look over my legs, though.

"Young scholar," she said, joining me at the study carrel. Less of the 'honourable' this time, I noticed. "Tell me about the priory."

"My name's Georgia," I said crossly before I could stop myself. I considered asking her how she knew where I'd been, but realised she hadn't the patience to indulge me. I gave her a (very) edited version of the party, glossing over how I came to be in the room, and asked if I'd experienced a ghost.

She nodded. "And what are you going to do about it?"

"Do I have to do anything?"

"Of course. You've been chosen by the book. It's your duty to put the poor girl's spirit to rest." I must've looked a bit lost, because her face softened very slightly. "Start with her story, the solution will present itself." She pointed me in the direction of the archives section of the library. "Ask yourself, Georgia: why is it called The Old Priory? Start from there. And remember what I said about lust..."

I turned round as I stepped away from that bay of shelving. "By the way, last night there was this thing in the cellars at work..." I needn't have bothered, the little grey lady was gone again.