It wasn't going to be that simple. We hadn't gone more than a dozen paces when a doorknob rattled, and something came shooting out of a classroom in front of us.

It was Peeves. He caught sight of us, and gave a squeal of delight.

"Shut up Peeves — please — you'll get us thrown out."

Peeves cackled.

"Wandering about at midnight, ickle firsties? Tut, tut, tut. Naughty, naughty, you'll get caughty."

"Not if you don't give us away, Peeves — please," I said, my heart starting to hammer loudly in my chest. If I got expelled, Father's anger would be too much for me to survive, I was sure.

"Should tell Filch, I should," Peeves said in a saintly voice, his eyes glittering wickedly. "It's for your own good, you know."

I flinched a little at those words, remembering the Sorting Hat saying the same thing just before turning my whole life on its head.

"Get out of the way," Ron snapped, taking a swipe at Peeves.

This was a big mistake.

"STUDENTS OUT OF BED!" Peeves bellowed, and I flinched once again. "STUDENTS OUT OF BED DOWN THE CHARMS CORRIDOR!"

I stood, completely frozen, and Hermione had to grab my hand and pull me after her to make me run with the rest of them. Ducking under Peeves, we raced to the end of the corridor, where we slammed into a door — and it was locked.

"This is it!" Ron moaned, as he, Harry, and Neville pushed helplessly at the door. "We're done for! This is the end!"

I could hear footsteps — Filch was running as fast as he could towards Peeves' shouts.

"Oh, move over!" Hermione snarled. She grabbed Harry's wand, tapped the lock, and whispered, "Alohomora!"

The lock clicked, and the door swung open; we piled through it, shut it quickly, and pressed our ears to it, listening.

"Which way did they go, Peeves?" I heard Filch ask.

"Say 'please'."

"Don't mess me about, Peeves, now where did they go?"

"Shan't say nothing if you don't say 'please'!" Peeves said, in his annoying sing-song voice.

"Alright — please."

"NOTHING! Hahaaa! Told you I wouldn't say nothing if you didn't say please! Haha! Haaaa!"

I heard the sound of Peeves whooshing away, and Filch cursing in rage, then turned away from the door to take a look at our surroundings.

And then I froze.

"Uh... Mione..." I said, my voice shaking a little as I tried not to scream.

Because we weren't in a room, like I'd thought we were. We were in a corridor. The forbidden corridor on the third floor. And now I knew why it was forbidden.

I was looking straight into the eyes of a monstrous dog, which filled the whole space between the floor and the ceiling — and it had three heads. It was standing quite still, all six of its eyes fixed on us, and I knew the only reason we weren't already dead was that our sudden appearance had taken it by surprise. But it was quickly getting over that — there was no mistaking what those thunderous growls meant.

In the space of a couple of seconds, my eyes had taken in everything about the corridor, trying to work out why the dog was there. And then I saw it — a trapdoor, right under one of its colossal paws.

Then the door opened, and we all fell backwards; Harry slammed it shut again, and we ran, almost flew, back down the corridor. Filch must've hurried off to look for us somewhere else, because we didn't see him anywhere, but I hardly cared — all I wanted to do was put as much space as possible between myself and the dog.

We didn't stop running until we finally reached the portrait of the Fat Lady on the seventh floor.

"Where on earth have you all been?" she asked, looking at our dressing gowns hanging off our shoulders, and our flushed, sweaty faces as we tried to catch our breath.

"Never mind that — pig snout, pig snout," Harry panted.

The portrait swung forwards, and we scrambled into the common room, where we collapsed into some of the armchairs. For a long time, none of us said anything. In fact, Neville looked as if he'd never speak again.

"What do they think they're doing, keeping a thing like that locked up in a school?" Ron eventually asked. "If any dog needs exercise, that one does."

By now, Hermione had got both her breath and her bad temper back again.

"You don't use your eyes, do you?" she snapped. "Didn't you see what it was standing on?"

"The floor?" Harry said. "I wasn't looking at its feet, I was too busy with its heads."

"Or maybe you didn't notice — there were three!" Ron added waspishly.

"It was standing on a trapdoor," I said. I seemed to be the least scared of what we'd just seen. Not that I wasn't scared, because I was, at least a little — but I was more than used to being in harm's way by now. To me, it was a fact of life, like breathing.

"Exactly," Hermione said. "And that means it can't be there by accident. It's obviously guarding something."

"Guarding something?" Ron said, staring at her.

Hermione stood up, glaring back at them.

"That's right. Now, if you two don't mind, I'm going to bed, before either of you come up with another clever idea to get us killed — or worse, expelled."

She walked away, up the stairs to the girls' dorms. I quickly got up and followed, slipping silently into the dorm after her, my mind ticking away.

As Hermione had said, the dog was clearly guarding something — I mean, why else would you put it in a corridor on top of a trapdoor? But what could it be guarding?

I thought back to an article that had appeared in the Prophet at the start of August — a break-in at Gringotts — and wondered if it was connected in some way.

Hermione, it seemed, had also been thinking about what lay under the trapdoor.

"Whatever that dog's guarding, it must be really dangerous, or really valuable," she whispered, as she got into bed.

"Or both," I added. "Did you hear about the break-in at Gringott's a month or so ago?"

"No, what happened?"

"Just like I said — someone broke into one of the vaults. And they managed to get out again without being caught, which is supposed to be impossible!"

"What did they take?" Hermione asked, sounding both interested and thoughtful.

"Nothing — the vault they'd broken into had been emptied earlier the same day," I said. "But all the same, there was talk of a very powerful Dark witch or wizard at play, and lots of people were worried that He Who Must Not Be Named was behind it. They always are, though, even if it's clear the slightly odd thing has no connection to Dark magic."

Hermione stared at me, her mouth a perfect 'O'.

"You think it might be connected?" she said, and I nodded.

"It would've taken far longer than a day to empty out a vault if there was anything substantial in there, so it can't have held that much in the first place — and Hogwarts is supposed to be about as safe a hiding place as Gringotts, perhaps even more so." I frowned for a moment as I thought. "So the question is, what's valuable enough to risk breaking into one of the most secure buildings in Britain for it?"

***
A/N: yes, I stole the chapter title from Sherlock. I was too lazy to think of one myself 😂

Also, a (rather late) merry Christmas to those of you who celebrate it!

Word count: 1256