Filch's office was located on the ground floor of Hogwarts Castle, at the end of a corridor that few people passed by after dusk.
The office was always filled with a smell that was a mixture of fishy odor, old rags, and kerosene lamps. A few oil lamps hanging from the ceiling cast a dim yellow light on the shelves crammed with confiscated items, making everything look dusty and gray.
Filch was sitting behind his chipped wooden table, clutching a worn-out quill pen, writing something in a thick disciplinary record book.
Suddenly there was a knock on the door.
When he looked up, the irritated expression on his face hadn't completely disappeared.
But when his gaze fell on the figure at the door, a look of surprise immediately appeared on his wrinkled face.
" Headmaster Dumbledore!"
He practically sprang to his feet, the chair legs scraping against the stone floor with a piercing screech, and rubbed his hands on his tattered clothes.
"What brings you here? Is there anything I can do for you? Which student has gotten into trouble again? Peeves? It must be Peeves-- "
"No, Mr. Filch." Dumbledore stood in the doorway.
His silvery-white beard gleamed with a faint, warm light under the lamp, and his blue eyes behind his Half-moon Spectacles held a gentle, reassuring smile.
"No students have committed any offenses; I'm just here to pick up something."
Filch paused for a moment, his hands slightly outstretched at his sides, as if unsure where to put them.
"Retrieving something? Headmaster, what do you need? I have—I only have confiscated stuff here, nothing of value—"
"Oh, you might not remember, it was a map," said Dumbledore.
He took a step into the office, his tall figure standing out prominently among the shelves piled high with miscellaneous items.
"A foldable map made of old parchment, with probably no writing on it, or writing that is illegible."
Filch's expression changed from respect to confusion, then he frowned as if searching his mind for something.
"Map?" he repeated the word, as if to make sure he hadn't misheard.
"Headmaster, I don't quite understand—which map are you referring to? The floor plan of Hogwarts?"
"I have a copy of that in my filing cabinet; it's something I kept from before—"
"It's not a map of the school." Dumbledore shook his head, his tone very patient.
"It's one of those student-made maps. Many years ago, a few students made a special map, which was later confiscated and should still be with you."
Filch's brow furrowed even more.
He turned around, facing the rows of shelves crammed full, his gaze sweeping from one floor to another.
"A map made by a student..." he muttered, pointing at the messy things on the shelf.
It included a small bottle of shrinking potion, a box of crackling firecrackers, three magic wands twisted into pretzel shapes, and a fake mouse that was still slightly wriggling...
"I've received quite a few things from students, but maps—maps—maps—"
He crouched down and pulled open a tin box on the bottom shelf, inside which was a thick stack of rolled-up parchment.
He flipped through the papers, pulled one out, unfolded it, glanced at it, and then put it back.
"No, this is a note passed in class." He pulled out another one. "None of these either... this is just some random drawing."
Filch plopped down on the ground, placed the tin box on his lap, and began flipping through the pages one by one.
He wasn't moving very fast because some of the parchment was rolled up too tightly, and he had to pry it open little by little with his fingernails.
One sheet was covered with moving stick figures fighting each other; another was filled with nonsensical sentences, which looked like some kind of code.
Dumbledore stood quietly to the side, his gaze fixed on the shelves as if he were looking at a rather uninteresting exhibition.
After a while, Filch pulled out a neatly folded piece of parchment from the bottom of the box.
That piece of paper was older than the others; the color at the creases was a shade darker than the rest, as if it had been folded and turned many times.
Filch unfolded it, turned it over, and glanced at the front.
There was nothing on it, it was completely clean, like a blank page torn from an old notebook.
"Headmaster," Filch said, holding up the parchment with a somewhat uncertain look on his face, "You mean this? A blank piece of parchment?"
Dumbledore glanced down at the parchment, then nodded.
"That's it."
When Filch handed over the parchment, his fingers hesitated slightly, as if he felt he was handing over something rather inappropriate.
Dumbledore took it, rolled up the parchment, and stuffed it into the inside pocket of his robe.
"Thank you very much, Mr. Filch," he said.
Filch stood up from the ground, wiped his hands on his clothes again, and looked more relaxed than before.
"You're welcome, Principal, you're welcome," he said.
"But let me ask you one more question, is there anything special about this thing? I've had it for years, and it's always just a blank piece of paper."
"It was made by a few students many years ago," Dumbledore said. "I want to see if it still works."
Filch nodded as if he understood, though he didn't quite get it, but he never asked the principal for something a second time.
Dumbledore turned and walked out of the office.
He quickly reached the corner of the corridor and took the parchment out of his pocket again.
The corridor was quiet, with only the faint sounds of dishes being cleared from the direction of the underground kitchen, and a few portraits dozing off in their frames, emitting soft snores.
He pulled the Elder Wand from his sleeve, gently pressed the tip against the folded parchment, lowered his eyes, and whispered a phrase.
"I solemnly swear that I will not do any good deeds."
The surface of the parchment seemed to be pushed from the inside by something, and the ink spread outwards like a fine spider web from the point touched by the tip of the stick.
Lines emerged one after another, first the main corridors and staircases, then the room layouts on each floor, and finally, countless tiny ink dots that moved slowly across the paper like ants.
Each ink dot is accompanied by a small name.
Every inch of Hogwarts Castle was laid out on that parchment, even the corners and secret passages that Dumbledore himself barely remembered were all clearly drawn on it.
Dumbledore's gaze moved down from the top of the map.
This was certainly not the first time he had seen this map.
Today, when he read its description in the book, he already guessed how this thing worked.
Hogwarts Castle itself possesses some kind of ancient magical contract, and everyone who enters the castle is recorded in some kind of unseen archive.
That map was made based on this principle; it could read the castle's records of those people and then project them onto the parchment as ink dots.
Whoever is in the castle, their name will appear on the map.
Whatever other people's names are, that's what their names will be displayed on the map.
No matter what that person becomes, no matter what disguise he uses, the castle remembers his real name.
Dumbledore held up the map, his gaze slowly sweeping across the various levels of the castle.
He brought the map this time only to confirm one thing: whether Sirius Black had infiltrated Hogwarts at some point.
Since escaping from Azkaban, Black has not been tracked by any Ministry of Magic means. If he is still active somewhere outside Azkaban, then Hogwarts is his most likely target.
Because Harry is here.
Dumbledore's gaze swept from the Gryffindor Tower to the Slytherin cellars, and then from the Astronomy Tower to the entrance to the Hufflepuff Common Room next to the kitchen.
Sirius Black is not currently known by that name.
It's not on the entire map.
He frowned slightly, but didn't seem too surprised.
It would be strange if Black had actually infiltrated the castle.
He was able to escape from Azkaban twelve years ago, but that was due to his good luck and resolute will; it doesn't mean he could cross the border defenses of Hogwarts.
Dumbledore was about to fold the map back up and put it back in his pocket when his gaze inadvertently swept over the floor of the Gryffindor boys' dormitory.
In the dormitory area, several familiar names were scattered around their respective beds.
Harry Potter, Ronald Weasley, Seamus Finnigan, Dean Thomas, Neville Longbottom.
Dumbledore's gaze slid over the names, and just as he was about to look away, he suddenly stopped.
His gaze was fixed on the parchment, as if nailed to it by something.
Next to Ronald Weasley's ink dot, almost right next to it, almost overlapping it, floats another name.
The name was very small, smaller than everyone else's, like some kind of inconspicuous label.
But the letters were clearly arranged on the parchment--
Peter Pettigrew.
Dumbledore's fingers froze instantly.
He stood at the corner of the corridor, parchment held up in front of him, his silvery-white beard slightly lowered, as if he had been Petrificus Totalus in an instant.
In the corridor behind him, several portraits were still dozing off, and an oil lamp at the end of the corridor swayed gently in the wind.
But Dumbledore's blue eyes were fixed on that name as he stood silently in the corridor, like a statue, motionless.