Dumbledore sat in his office, quietly studying a document spread across his desk.
In addition to being the Headmaster of Hogwarts, he held several other responsibilities—Chief Warlock of the Wizengamot, Supreme Mugwump of the International Confederation of Wizards, among others.
Because of this, he had to divide his time between managing Hogwarts and handling affairs beyond the school.
When Sherlock entered, Dumbledore looked up, set aside his quill, and smiled.
"Would you care for some dessert with afternoon tea?"
Almost as soon as he spoke, a small plate of cookies and two cups of steaming black tea appeared on the desk.
"Thank you, Professor, but I've just come back from tea with Professor Sprout and the others at the Three Broomsticks."
Sherlock said this as he took a seat across from him.
Dumbledore lifted his teacup, adopting the posture of a patient listener.
"Then I assume you've come for something else?"
Sherlock didn't waste time.
"It's about the attacks that have been happening in the castle this term, Professor."
Dumbledore's expression grew more attentive.
"Oh? Have you discovered something?"
"News of the situation has already spread outside the school. Today, at the pub, I heard a rumor. I'm not certain of its truth, so I came to confirm it with you."
Sherlock's tone was steady, but serious.
Dumbledore slowly set his teacup down.
"And what is this rumor?"
"That fifty years ago, the Chamber of Secrets was opened… and that Hagrid was expelled because of it."
Sherlock spoke calmly. There was no accusation in his voice—only a desire for confirmation.
Dumbledore did not hesitate.
"That is correct."
He spoke plainly, as if discussing something ordinary.
"It happened fifty years ago. I was not Headmaster at the time. Though I wished to prevent them from placing the blame on Hagrid, I lacked the authority. The best I could do was ensure he remained at Hogwarts, so he would not be cast out into the world."
Sherlock frowned slightly.
"So the Chamber truly was opened before… and Hagrid was implicated?"
This time, Dumbledore did not answer immediately.
He regarded Sherlock silently, as though weighing a decision.
Sherlock remained quiet, waiting.
After a brief pause, Dumbledore rose from his chair.
"Since you already know this much… would you like to see what happened for yourself?"
His blue eyes shone with quiet clarity.
Sherlock nodded without hesitation.
Dumbledore walked to a cabinet and retrieved a shallow stone basin, placing it carefully on the desk.
Then he raised his wand to his temple and gently drew out a strand of silvery light, as though pulling a thread from his own thoughts, and lowered it into the basin.
"The Pensieve," he explained. "I use it to store and examine memories. It helps me see things more clearly."
He gestured toward it.
"And now, it can show you the past."
Sherlock stepped forward. The surface of the basin shimmered with drifting strands of light.
He leaned down and let himself fall into it.
A sensation like plunging through air engulfed him—weightless, disorienting—until suddenly his feet touched solid ground.
The darkness around him faded.
He found himself standing in a corridor of Hogwarts.
Night had fallen; outside the windows was pitch black. Only flickering torches along the stone walls illuminated the passage.
A moment later, Dumbledore appeared beside him.
Sherlock took in the surroundings—the same castle, yet unmistakably different.
"Is this Hogwarts from fifty years ago?"
"More precisely," Dumbledore replied softly, "this is Hogwarts as it existed in my memory."
Just then, a tall wizard with long auburn hair and a flowing beard walked past them.
He bore a striking resemblance to Dumbledore.
Dumbledore gestured for Sherlock to follow.
"Is that you?" Sherlock asked, a hint of curiosity in his voice.
Dumbledore nodded.
"At the time, I was merely a Transfiguration professor."
They followed the younger Dumbledore down the corridor toward the Entrance Hall.
There, they saw a handsome boy wearing a prefect badge.
The young Dumbledore stopped him.
"What are you doing out so late, Tom?"
The boy remained calm and composed.
"I was on my way to see the Headmaster, sir."
"Then you should return to your dormitory," the young Dumbledore said, studying him with a piercing gaze. "It's not safe to wander the castle these days… not after what has happened."
He trailed off with a sigh.
Sherlock lowered his voice.
"The attacks had already begun at this point? A student had died?"
Dumbledore nodded gravely.
"Yes. The situation was severe enough that the school was considering closing."
They watched as the young Dumbledore and the boy named Tom parted ways.
But then Dumbledore placed a hand on Sherlock's arm, stopping him.
"We cannot follow events I did not personally witness," he explained. "But you will soon see the outcome."
They stood still in the Entrance Hall.
Moments passed.
Then—
A deafening explosion erupted from the dungeons below.
The stone floor trembled violently beneath their feet.(TN: This is not canon.)