The streets had begun their slow surrender to dusk.
One by one, shop signs woke from their daytime sleep, spilling red, blue and white across the rain-dark pavement. Yesterday's puddles caught the colors and stretched them into wavering ribbons beneath passing feet. Somewhere beyond the crowded skyline, the last of the sun disappeared without ceremony, leaving the city to its own lights.
Violet left the main road without a word.
She slipped into a narrow lane between two apartment buildings, moving with the ease of someone who had memorized every turn long ago.
Yè Yī noticed immediately.
"...Can we trust her?"
She didn't break stride.
"Mhm."
That was all she offered.
Qiū Huà Bǐ followed several paces behind, hands buried in the pockets of his hoodie.
His attention wandered naturally, not because he expected danger, but because he had never learned how not to notice things.
An old surveillance camera hung above a convenience store doorway.
One apartment window stood open despite the cold.
A delivery motorcycle idled at the end of the street longer than necessary before finally pulling away.
Nothing looked unusual.
Ahead of them, Mù Xiāo Xiāo walked without slowing.
She never checked whether they remained behind her.
She seemed to know they would.
The alley bent twice before widening again.
Without warning, the buildings fell away.
The city opened around them.
The library stood quietly at the center of the square.
Age showed in the pale stone walls and broad front steps polished smooth by decades of passing feet, yet nothing about it felt old. Glass stretched upward between carved columns. Warm light poured through tall windows, turning the interior into a lantern against the deepening blue of evening.
Above the entrance, elegant bronze characters caught the light.
CITY ARCHIVES & BOOKHOUSE
Students climbed the steps carrying backpacks heavy with textbooks.
An elderly couple emerged with paper bags filled with novels.
A father knelt beside his daughter near the entrance, helping her sound out the title of a picture book before she proudly carried it inside herself.
Life flowed through the building without interruption.
The place wasn't hidden.
It wasn't forgotten.
If anything, it was one of the busiest buildings in the district.
Qiū Huà Bǐ slowed.
"...We're here?"
Violet watched the people moving through the doors.
A faint smile touched her face.
"Mm."
The smell of fresh coffee, paper and wood polished so many times its grain had softened beneath generations of hands reached them before they stepped inside.
The scent reminded Yè Yī of long afternoons spent studying alone.
For a moment, it almost felt familiar enough to forget everything Violet had shown him these past few days.
Well.. almost.
The library breathed quietly around them.
Rows upon rows of shelves stretched upward beneath warm lighting that never felt harsh. Readers drifted between them with practiced patience. Somewhere above, a printer hummed before falling silent again.
A librarian pushed a cart overflowing with returned books.
Someone whispered an apology after bumping another reader.
Near one of the windows, two university students argued softly over a stack of engineering textbooks while pretending not to disturb anyone else.
Nothing asked to be noticed.
Everything just seemed to belonged.
Qiū Huà Bǐ looked around once, then again.
His brow slowly drew together.
"...Wait."
He looked at Violet.
"...This is Factor IV?"
She nodded.
"People spend too much time hiding secrets underground."
Her gaze wandered across the reading hall.
"So nobody ever thinks to hide them somewhere they already trust."
She shrugged.
Qiū Huà Bǐ stared another second.
"...You've got to be kidding."
"No."
Yè Yī spoke almost to himself.
"...I've been here."
Violet glanced sideways.
"I know."
He looked around again.
"The history section."
"You borrowed three books."
He stopped walking.
"...You know that too?"
She only gave her now 'almost signature' half-smirk.
Qiū Huà Bǐ rubbed the back of his neck.
"I practically lived here during finals."
"Fourth floor," Violet replied.
"The corner desk beside the window."
He blinked.
"...That's creepy."
"I have excellent memory."
"...That's somehow creepier."
For the first time since entering the building, Yè Yī almost smiled.
It disappeared before anyone could be certain it had happened.
Violet noticed anyway but she pretended she hadn't.
"Come on."
She continued deeper into the library.
The others followed.
The public shelves gradually gave way to quieter corridors where fewer readers wandered.
The conversations faded behind them until only the turning of pages remained.
Mù Xiāo Xiāo finally stopped before an ordinary aisle.
Nothing marked it as special.
Tall shelves stood shoulder to shoulder beneath soft ceiling lights, filled with aging records and local archives few visitors ever seemed interested in.
Qiū Huà Bǐ frowned.
"...This?"
Mù Xiāo Xiāo rested one hand against the side of a shelf.
Between two rows of books, a narrow strip of dark glass caught the light.
So narrow it disappeared unless someone already knew where to look.
Her palm touched it.
Nothing happened at first.
One heartbeat passed.
Then two.
A quiet click echoed somewhere inside the wall.
The shelves didn't swing outward.
They drifted apart almost silently, revealing an elevator hidden behind them so naturally it felt less like something opening...
...and more like something allowing itself to be found.
Qiū Huà Bǐ stared.
"...You've got to be kidding."
"No," Violet said.
"This time, we're here."
He looked from the hidden elevator to the crowded reading hall only a short distance away.
People continued reading.
A child laughed somewhere upstairs.
A librarian scanned another stack of books.
No one looked in their direction.
No one seemed to notice an entire section of shelves quietly moving aside.
"...How?"
Violet stepped into the elevator first.
"People rarely notice what isn't asking to be noticed."
The doors remained open.
She looked back at the three of them.
Her expression carried the same calm certainty it always did whenever she walked toward something everyone else considered impossible.
"Welcome to Factor IV."
A tiny smile appeared.
"...Try to look like you've been here before."
Qiū Huà Bǐ sighed as he stepped inside.
"I liked life better when libraries were just libraries."
Yè Yī followed without speaking.
Only Mù Xiāo Xiāo remained exactly as she always had.
She entered last.
The doors closed.
Outside, the library continued exactly as it had a moment before.
Readers turned pages.
Coffee steamed from paper cups.
Someone checked out a novel at the front desk.
No one noticed that four people had quietly vanished between the shelves.
And that was precisely why Factor IV had survived for so long.