Hogwarts: Lacus doesn't want to be a witch who destroys nations.

In the winter of 1938 in London, the smell of coal smoke was thicker than usual, and the leaden clouds hung low as if they were pressing into the cracks in the cobblestones of Baker Street. When the wooden door of apartment 221B was pushed open, the creaking sound was particularly jarring in the quiet corridor. Sherlock Holmes, leaning on his brass cane, slowly entered the room. Rheumatism made his right leg feel slightly stiff with each step, and Lux ​​followed behind him.

Holmes bought the building after Mrs. Hudson's death. By then, no one would be heating cocoa by the fireplace anymore, but he kept it as a temporary refuge and a place to reminisce, even though he hadn't been back for several years.

Pushing open the door, the atmosphere inside was exactly the same as when he left: the burnt smell of tobacco, the sour smell of developing solution, and the musty smell of damp old books.

The files on the bookshelf were covered in a thin layer of dust, and a map of London lay open on the desk by the window, its edges worn smooth from being rubbed by fingers. Holmes draped his wool scarf over the back of his chair, coughed twice, and the years had softened his chest, making even his breathing heavy and muffled.

He picked up the newspaper on the table; the front page headline, printed in bold, read, "Prime Minister Chamberlain: We have won a generation of peace," accompanied by a photo of the prime minister waving the agreement as he returned from Munich.

"Peace?" Holmes scoffed, his fingertips tracing the edge of the newspaper. "It's nothing more than an excuse to postpone the storm."

"Sit down." Holmes gestured to the sofa, then walked behind the desk and sat down, taking out a tin box from the drawer containing an unlit pipe.

"I am indeed getting old. You, who came out later, easily arrived at Baker Street to wait for me before me."

He didn't light a cigarette, but just held the pipe stem, his gaze sweeping over Lux: "Now, show me your magic. Don't use those street-smart props, I want something more concrete."

Lux put down the basket, and Lumi poked her head out, staring curiously at the galvanometer on the table, her little paws scratching at the edge of the basket. "No problem!" She pulled a wand from her robes and walked to the center of the room. "Let's start with something easy: Fluorescent Blink!"

A soft white light instantly appeared at the tip of the staff, not flickering like a candle, but as stable as a solidified ball of light.

Holmes immediately stood up, picked up a magnifying glass, and leaned closer. He then gestured for Lux to stay still, quickly walked to the corner, aimed the camera obscura at the light, adjusted the lens, and pressed the shutter—"click!"—the film began to expose. He then picked up a thermometer and carefully approached the light. The mercury column, which had initially shown 12°C, slowly rose to 18°C, but the air around the light did not feel hot at all.

"It generates heat without an open flame, and the heat is concentrated within the light itself," Holmes muttered to himself, noting the thermometer reading in his notebook. "Let's try another one."

Lux flicked her wrist, dropping the teacup onto the ground where it shattered into pieces. Holmes slowly crouched down and rubbed the fragments with his fingers; the teacup was indeed broken.

"Restored to its original state!"

The teacup immediately returned to its original position on the ground. Holmes' eyes lit up, and he immediately brought the galvanometer probe close to the teacup. The pointer did not move at all, ruling out the possibility of current interference.

"The exposure time of the camera obscura is sufficient." Holmes turned off the camera obscura, walked to the bookshelf, took out a book, turned to a certain page, and closed it again. "It's not light reflection, not chemiluminescence, and not electric current driving; this is indeed not something humans can do."

He finally sat back down in his chair, a look of relief appearing on his face for the first time. "Now, I can tell you why I barged into that club."

Holmes turned and took a wooden box from the drawer. Inside was a stack of files and a yellowed letter.

He handed the letter to Lux, "Take a look at this first."

Lux took the letter, but froze as soon as her fingertips touched the paper. It was parchment, a type of paper that Muggles had abandoned for centuries, and which was basically never used except for very important legal documents.

Although it was a common writing material in the wizarding world, Muggles almost never used it. She unfolded the letter; the handwriting was strong and vigorous, with a distinct English calligraphic style, but the content made her pause again:

"Dear Sherlock:

Forgive me for contacting you in this way, but recently there have been a series of bizarre deaths in East and South London. The victims were all Muggles, and their bodies had severe lacerations, as if they had been attacked by a large animal, but there were no animal footprints at the scene.

I'm worried this isn't an ordinary wild animal attack. If you have time, please investigate. Be careful and don't let those people find you.

Your old friend John Watson

December 15, 1938

"Watson?" Lux looked up. "Dr. John Watson? Your partner?"

Lux looked at it more closely and suddenly realized something was wrong: "The word 'Muggle' is clearly a wizard's term, and the ink in this letter is too dark, as if it was just written, and your old friend... I remember he has been dead for a long time."

"Yes," Holmes's voice was heavy. "He died in the summer of 1929, and this letter is dated two weeks ago; it's clearly a forgery."

Then a hint of approval flashed in Holmes' eyes: "You are very observant. At first, I also thought it was some kind of prank, but I haven't been back to London for a long time, so I came back to visit on vacation, until I saw this photo."

He pulled out a black-and-white photograph of a Muggle corpse with a deep, bone-revealing laceration on its chest, with some silver hair still clinging to the edges. "This case is real. I went to the crime scene in the East End. The victim was a baker who died at the back door of his bakery. There were obvious bite marks around the wound, and the teeth were spaced far apart. It couldn't have been caused by a bear, a wolf, or any known British wild animal."

Holmes then produced a glass tube containing several coarse, silver-black hairs: "These were found next to the corpse. I sent them to zoologists for analysis, and they said they didn't belong to any known land mammals. There was also an unknown substance remaining in the hairs, but now I know—it's magic, isn't it?"

Lux leaned closer to the glass tube and gently tapped it with her wand. A faint golden light emanated from the tip of the wand. When the golden light touched the hair, a wisp of black mist flashed across the surface of the hair for a moment before disappearing.

"It's remnants of dark magic!" Lux's expression turned serious. "This fur... it looks a lot like what a werewolf would have!"

"Werewolves? Cough cough..." Holmes coughed twice, took a leather notebook from the drawer, "You mean, the legendary creature that transforms under the full moon? I looked up folklore when I was young, but I've never seen any evidence of it."

He opened the notebook, which contained several black and white photographs. The first was of the baker's body, with jagged edges on the lacerations in his chest, the wounds so deep that the bone was visible. The second was of the footprints at the scene, with obvious scratches on the toes. The third was a yellowed map of London, with several crime scenes in the East and South Ends marked in red, each circle accompanied by a date, all around the full moon.

"I investigated the whereabouts of the deceased," Holmes' voice was hoarse with age. "The first victim was a baker who had been to an abandoned warehouse near Charing Cross before he died; the second was a coachman who was found in an alley around the warehouse; the third was a flower girl whose body was found at the back door of the warehouse—all the clues pointed to that warehouse, but my informant said that there was only dust and rats in the warehouse, not even a wild animal in sight."

"So I searched the street corner for a long time, until I felt my mind was becoming a little hazy, when suddenly I saw someone open a door in front of me," Holmes recalled. "Just a few minutes ago there was nothing there, but suddenly a building appeared, so abruptly yet so logically."

"Sir, this is normal, because of the Secrets Act. It's too complicated to explain in detail, but basically, wizards must be kept separate from Muggles, so there are a lot of forgetting and confusion spells in this place to shield Muggles."

Lux thought for a moment, "The fact that you can see the Leaky Cauldron bar most likely means that a spell has failed."

"I see." Holmes shrank back in his chair. "Before I left, I overheard those wizard policemen mentioning saints, saying they were looking for someone. Could it be related to this?"