This was originally written for the 2017 HP Horror Fest on LiveJournal. Thanks to the Dark Arts community I discovered the lure of the dark side, so I keep coming back for more.
Thanks to my amazing beta Hiril this story has been improved immensely – any remaining mistakes are my own.

Chapter 1

-oOo-

The door was still open, as if someone had left in a rush. Inside the dormitory, Minerva was greeted by the familiar detritus left behind by students wherever they went, rather like slugs leaving tracks of slime.

A lonely sock. An open book – the fifth year Charms textbook, if she was not mistaken. A pile of damp Quidditch robes, discarded on the floor in a pile. That was useful – whatever had happened here, it had occurred before the house-elves had got time to clean up.

Minerva was probably the first living being setting a foot here since yesterday.

She glanced at her watch – it was past midnight. In magical terms that meant the start of a new day, although the dark windows bore no trace of dawn. For tired witches, it was still night. Minerva's hair was still holding up, reinforced as it was with charms and hairpins, and she kept her back straight as if the whole edifice would tumble down should she allowed herself to unbend just a fraction.

It had been a long evening, and the night promised worse.

Minerva had been annoyed when the Gryffindor prefect knocked on her door – she had only just finished her marking, and she had contemplated the possibility of having a dram of whisky before bed. She wouldn't, of course, but considering it had made her feel as if it were possible to carve out a bit of time for herself during term, in between lessons, planning and marking, and managing a herd of unruly Gryffindors.

"Professor," Mary Ferguson had said when Minerva opened the door, and it was obvious the girl already regretted coming to see her. Mary was a sensible girl (as much as any sixteen-year-old could be), rarely in two minds about anything other than whether to apply to join the Unspeakables or the Department of Magical Law enforcement.

Minerva had regretfully abandoned all hopes for a peaceful hour before bed. "Yes, Miss Ferguson?" she asked, taking care not to let her irritation seep through. "Is something the matter?"

"It's Rupe – Rupert Barrington, Professor. He says they're all gone." Mary frowned. "I don't think they – I mean, normally it would be Rupert, Bill and Shane getting up to something, if anything."

"Yes," Minerva agreed, passing the last six years under quick mental review. Rupert Barrington, William Weasley and Shane O'Sullivan had certainly been responsible for more than their fair share of rule-breaking, and they would generally stick to their own little group. "Who are 'all' of them?"

"Why, the other boys in his dorm: Bill, Shane, Vijay and Daniel. Rupert says they've been gone all evening. Bill was supposed to be at Quidditch practise, but he never showed up."

"Wait a moment, please." Minerva summoned her teaching robes – thanks Merlin she hadn't had time to change into her pyjamas – and grabbed her hat from its hook by the door. "Where is Mr Barrington now?" Minerva set a brisk pace towards Gryffindor Tower and Mary did her best to keep up.

"I told him to wait in the common room with Hector." The Rosier boy was the second Gryffindor prefect. It had been a bit of a risk to make him prefect, as he seemed to believe a Gryffindor should act first and think later, but Minerva had hoped Mary would have a sobering influence on him.

When they entered the Gryffindor common room, Minerva had the small satisfaction of seeing she had been right: Hector had wrapped a blanket around Rupert's shoulders and was speaking softly to him.

"Well done, both of you," she said. "Ten points to Gryffindor. Now, Mr Barrington, please tell me what has happened. All of it."

Rupert looked startled and she smiled inwards at the perpetual innocence of students; they never realised the teachers had been in their place once. In fact, on that very chair –

Now was not the time for reminiscences, however fond, and Minerva pushed the memories of her reprobate youth to the back of her mind. "In your own time, Mr Barrington."

"I haven't seen any of them all night. After Potions, I had to go down to the hospital wing to see Madam Pomfrey. I had pus coming out of my ears, it was really disgusting. You wouldn't believe the stench..." He seemed almost proud of his calamity.

Minerva remembered there had been an accident in Potions that day. Severus had been especially scathing on the subject of cack-handed students in the staffroom.

"I had to stay for a bit, so I missed dinner. It took Madam Pomfrey ages to get rid of all of it. When I came back, they weren't here. I thought they would turn up later, but they haven't. None of them, not even Vijay, and he always goes to bed at ten." Rupert clearly considered early bedtime fit only for first-years.

"Were any of them at dinner?" Minerva asked the two prefects, who nodded. "Did they come back here afterwards?" It had been a wet afternoon, with a thick mist wrapped around the castle – not very tempting for outdoor pursuits.

"I think so," Mary said slowly. "Vijay said something about a Potions essay –"

"It's due tomorrow," Rupert interrupted. "Snape was in a right mood – Professor Snape was rather annoyed in class," he corrected himself under Minerva's admonishing glare, although she tucked away the nugget to tease Severus with later. "Most of us in fifth year had to work on it after dinner."

"I saw Shane going upstairs just after dinner," Hector added. "I'm pretty sure Bill and Daniel were here too, but I wouldn't swear to it."

"And you haven't seen either of them since?" Minerva asked, and all three of them shook their heads. She wasn't very concerned yet, and Severus' essay was a possible explanation. While these four students were not the ones she would have picked out as likely to be absorbed in their homework, forgetting the time, stranger things had certainly happened at Hogwarts.

It occurred to her she had neglected the most logical explanation, but a quick Homenum Revelio failed to reveal any Disillusioned students lying in wait for Rupert. If it were a prank, they were hiding somewhere else.

"I'm afraid I'm going to have to ask you to wake up some of your housemates," she informed Mary and Hector. "Please find out if anyone has seen either of the boys, and if so, when and where. You can start with their friends. Please try not to wake up the younger ones if you can avoid it."

Minerva was under no illusion that most of the older students were probably still awake, hiding in their dormitories for her benefit. The clock had just struck eleven when she had put her marking aside, and judging by how hard it was to get them to pay attention in their first class of the day, her Gryffindors were a parliament of night owls.

While Hector and Mary scurried away to the dormitories, she turned around to an anxious-looking Rupert.

"Are you sure that's all you have to tell me, Mr Barrington?" She used the full force of her teacher glare on him, the one that made even Albus fidget. "Is there anything you would like to add?"

He squirmed, and then it all came bubbling out. "Shane said he'd found something, that he wanted to show us after dinner. Only I had to stay –"

"In the hospital wing, I know." Minerva interjected, not keen to hear more pus-filled details. "What did he find?"

"I don't know, only it was something really cool."

In Minerva's experience, the adjective (or any permutation thereof, depending on the fashionable vocabulary of the day) covered the gamut between the poster in the latest issue of Which Broomstick! and Dark artefacts.

"When did he find it?" she pressed. 'At the breakfast-table' would suggest something closer to the former than the worrying prospect of something Dark.

"Don't know." Rupert Barrington had not distinguished himself with his capabilities of independent reasoning, Minerva recalled from his essays ('Hair is harder to transfigure than eyebrows because it's bigger').

She tried to tease it out instead. "When did he tell you about it?"

"Not sure. I think it was yesterday."

"Where were you at the time?"

"Don't know, in class? Divination," he hastened to add. Fortunately, Sybill was probably having a nightcap up in the North Tower – no self-imposed abstinence for her – and didn't see Minerva's slight nod, to get Barrington to hurry along and forget the fact she was a teacher.

"He said we had to wait until tonight. It wouldn't work otherwise."

"It?" Minerva was running out of patience fast. Fortunately, Rupert was trying to visualise what had happened yesterday by screwing his eyes shut in the direction of the fireplace.

"It was something in our dorm, I think – he wanted to get rid of Vijay and Daniel. Only how he'd do that I don't know, Dan is always trying to find out what we're up to."

"Oh." Minerva wasn't sure whether to be relieved or disappointed – as the students patently were not in their dormitory now, her only clue seemed to be a red herring. Whatever 'cool' item Shane O'Sullivan had been talking about when he should have been studying tea leaves, it couldn't have anything to do with his disappearance.

She asked again, just to be sure: "And you can't remember anything else about it?"

"No, Professor."

Minerva sighed. There was nothing for it – she would have to wake up the others. Ten to one, Albus was conveniently away on Mugwump business; it was her hard-working fellow teachers she was concerned about. The last thing they needed was to be cast out from their comfortable rooms and dispatched into the chilly corridors to search for her errant students, but it had to be done.

At Muggle schools, she doubted the faculty regularly had to mount search parties for missing students.

At Muggle schools, the worst that could happen was illicit drug-taking behind the bike sheds. Minerva rather envied Muggle teachers sometimes. She still had to deal with the teenage hormones and the unstoppable drive to ingest banned substances, only with added magic.

"Mr Babbage?" The portrait woke up with a start, dropping his pink and purple turban in the process. "I beg your pardon for disturbing you, but I'm in urgent need of your help. Can you please inform the Heads of Houses their assistance is urgently needed in Gryffindor Tower?"

Filius was the first to suggest they ought to look inside the dormitory. A quick search of the most frequent haunts of miscreants had yielded nothing, and Severus and Pomona were busy laying the groundwork for a more extensive search. Severus' mouth was a thin line of disapproval; he was never one to condone the behaviour of Gryffindor rule-breakers.

"Why, do you think they're hiding under the bed?" Minerva snapped.

"No," Filius said mildly. "I've been reading Muggle books lately – there's only so much Gilderoy Lockhart a man can stand – and their Hit Wizards are very keen on what they call Clues."

"I know what a clue is, Filius – I was virtually raised on Sherlock Holmes."

Wise to her ways, he didn't push the matter, but he didn't look surprised when Minerva announced she was returning to Gryffindor Tower. Severus had roused Argus, who came equipped with encyclopaedic knowledge of the nooks and crannies of Hogwarts, and Mrs Norris. Few students could stay hidden from them for long, never mind four of them. When Argus returned empty-handed from his first round (he assured them he was going to do as many as it took, even if he had to keep going until dawn), Minerva decided she had better check in with her prefects.

If she happened to search the empty dormitory at the same time, that was her own affair.

Mary and Hector had surpassed her expectations; using a piece of parchment listing most of the older Gryffindors, they had drawn a complicated diagram they claimed showed all four boys had last been seen in the common room or heading up the stairs towards their dormitory. No one had seen any of them since about an hour after dinner.

"Well done," Minerva said briskly. "Twenty points to Gryffindor."

They looked pleased, but uneasiness soon took the upper hand again.

"We didn't try to – I mean, we've made sure no one has gone into their dorm," Mary said.

"Where's Mr Barrington?" Minerva suddenly wondered if she should have kept a closer eye on the boy, but she relaxed when Hector pointed to a snoring pile of assorted blankets on a transfigured bed next to the fire. "Very good. Please make yourselves comfortable – I may be a little while."

Hector curled up on the couch and Mary stirred the fire with a charm (her wand-work was getting better and better, Minerva noticed) as she briskly mounted the stairs to the boys' dormitories.

A thorough search unearthed no clues, obvious or otherwise. Sherlock Holmes himself would have been stumped. The great detective would of course not have had access to magic. Minerva did, but she still failed to detect any signs of the missing four.

Bearing in mind the amazingly fertile imaginations of teenage boys, she even checked the room for humans Transfigured into inanimate objects. Past students had certainly placed themselves in dafter situations than that.

It was no use – the boys were gone.

For the first time, Minerva wondered if she should send for Albus. None of the others had even suggested it, knowing his likely reaction. Students disappearing occasionally was a fact of life at Hogwarts. No doubt he would remind them the students usually turned up again, none the worse for their adventures.

While Minerva didn't hanker for a Headmaster wrapping the students in cotton wool like the Muggles did, she wished Albus would concern himself less with the inevitable rise of the next Dark Lord and more with the day-to-day realities of running a boarding school. Preferably with the objective of making it through the day with all students present and correct at the end, with the expected number of limbs. Healing charms were well and good, and wizards were very hard to kill, but Minerva preferred a minimum of physical trauma regardless.

The world outside school would knock some sense into them soon enough; Minerva didn't see the need to expose them to the cold realities of life on purpose before then. If one only paid attention, there were plenty of children facing problems beyond their tender years, long before they left Hogwarts.

Employing all the methods at her disposal, Minerva sighed and put her wand away. In the mirror on the wardrobe next to William Weasley's bed, she could see herself shrink, until her eyes had almost reached the floor. They changed shape as well, turning into little pinpoints of black surrounded by a vivid yellow, startlingly different to the staid brown of her human form.

The world looked different down here – paler and greyer, but with more layers than humans could dream of. She could hear students mumbling in the nearby dormitories, and occasional shouts from the search party outside.

Minerva yawned widely, bringing the scents lingering in the room into her mouth to dissect them. The smell of teenage boys was less tangible as a cat – human hormones meant nothing to them, so the odours clinging to unwashed clothes thrown around like confetti didn't offend her nose.

She had followed trails before, on Order business, but rarely in a confined living space where scent seemed to be layered upon scent in a mille-feuille of tracks. Hotspots like the pile of Quidditch clothing almost blinded her senses at first, but as she got used to following her nose, she learnt to tell the different scents apart.

The beds positively reeked of their usual occupants; Minerva jumped from one to the other, assigning a name to the scent before she moved on. Vijay's scent had a bitter twang, while Daniel's was cloyingly sweet (probably due to the Muggle deodorant he had smuggled in). Rupert smelled of dirt, cotton and parchment, more childlike than any of the others.

Once Minerva had them separated in her mind, she started sniffing in earnest, swinging her tail from side to side to focus.

There was something there – something fresh, without Rupert's notes of simple things, but with all the other scents mingled in the same place. It was a blank piece of wall between the bathroom and the entrance, halfway obscured when the door was left open – no doubt the reason why the inevitable posters with Quidditch and musicians had been fixed to the other walls instead.

It wasn't much, only bare stonework, and yet she was almost certain the four boys had congregated there. But why?

Maybe they had been desperate for the bathroom, she thought wryly – there was a reason all male teachers had voted unanimously to abolish the sinks inside the dormitories ten years ago. But surely they would just have nipped in next door?

She yawned again, stretching her mouth open so she was almost eating thin air in a last attempt to coax the truth out of the empty room before she changed back.

To human eyes, the wall was just as unremarkable. There was some graffiti – Sirius Black had been a busy boy a decade ago – but no clues. She even stroked the rugged stone with her paw, but it was the same uneven masonry one encountered in most of the castle.

The students had been standing together in front of the blank wall for some time. That was a clue in itself, but Minerva had no idea what to make of it. She didn't like being left in the dark at the best of times (an unfortunate trait in Albus' deputy), but it was deeply disquieting when her students had gone missing.

Perhaps the others had found something. She had better attend to Hector and Mary; they ought to be in their beds.

"Nothing?" Minerva asked Severus, who could have given any vampire a run for his money with his parchment-pale skin and deep, black eyes glowing in the torch-light. When others flagged, Severus kept going. Admittedly, he was the youngest, but Minerva rather thought he would have been searching with the same restless energy had he been a centenarian.

He didn't even rise to giving a sarcastic response to the somewhat redundant query, which was virtually unheard of.

"Nothing. Hagrid is talking to his friends," there was a definite sneer, "negotiating our entry into the Forest. Filius has Floo'd for assistance; we don't have the numbers for a thorough outside search."

"Did anyone wake Albus?" Minerva asked – if they were enlisting outsiders to help, this was hardly a minor matter anymore.

"Naturally. He has gone with Hagrid – " Severus started, but Minerva was destined never to find out if he was going to make a cutting comment or merely impart information, as a graceful creature she knew well landed in front of them.

"Kindly meet us at the edge of the Forbidden Forest – we have found them!" Albus' voice announced, and Minerva's knees suddenly gave out. She grabbed Severus arm, and despite her fingers digging into him hard enough to leave bruises, he mercifully didn't say anything.

He didn't let go of her arm, though, keeping a firm grip on it all the way down to the Forest.

To be continued next week