Hae-in did not open the envelope that night.
She placed it inside the evidence locker and entered it into the case log.
ITEM: ENVELOPE — MARKED "FOR HAE-IN — 18"
SOURCE: PARK EUN-SOOK
ORIGINAL AUTHOR: SEO JIN-WOO
DATE: UNKNOWN
Then she locked the cabinet.
Kang watched her.
"You're really leaving it there?"
"Yes."
"You're not curious?"
"I am."
"That didn't answer my question."
"It did."
He smiled faintly.
"Fair."
Hae-in picked up her coat.
"Tomorrow."
"Why tomorrow?"
"Because whoever left that photograph wanted me to open it tonight."
Kang glanced toward the evidence locker.
"And you don't want to do what they expect."
"No."
She switched off the office light.
"Not until I know why."
The next morning, the envelope was still sealed.
That was the first thing Hae-in checked.
The second was the photograph.
It was still in its evidence sleeve.
She placed it under the desk lamp.
Room 08.
Same walls.
Same concrete floor.
Same narrow ventilation opening near the ceiling.
But the photograph had been taken from a different angle.
The camera was standing inside the room.
Facing the door.
Which meant whoever took it had been standing inside Room 08.
Recently.
Hae-in enlarged the image.
There was something near the bottom corner.
A dark rectangular shape.
She printed it.
Then enlarged the print.
It was a metal plate.
Almost completely covered by dust.
Only four characters were visible.
C-08
Kang appeared behind her.
"Another door?"
"No."
She pointed.
"Look at the floor."
He leaned closer.
There were scratches around the plate.
Recent ones.
Something had been moved.
Kang straightened.
"Someone opened something."
"Recently."
"Could be the woman."
"Could be anyone."
He looked at her.
"You're getting more careful."
"I've been getting more careful for thirty-six chapters."
"That long?"
She gave him a look.
He raised both hands.
"Fine."
At ten, they returned to the municipal archive.
The clerk from the previous day brought them the remaining records concerning Jang Yu-ri.
"There isn't much," he said.
"There doesn't need to be."
Hae-in opened the file.
A personnel photograph was attached.
Jang Yu-ri.
Thirty-one.
Short hair.
Plain expression.
Nothing immediately distinctive.
Kang looked at the photograph.
"This isn't the woman from Room 08."
Hae-in looked at him.
"You're sure?"
"Yes."
"Why?"
"I saw her."
"From a doorway, in poor light."
"I remember her face."
Hae-in studied him for a moment.
Then returned to the photograph.
He was right.
The woman behind Room 08 had looked older.
Maybe forty.
Maybe more.
It was difficult to tell.
But she had not been Jang Yu-ri.
Hae-in turned the page.
A handwritten note had been attached to the back of the personnel photograph.
TRANSFERRED — 18 APRIL 2008.
No destination.
No signature.
She looked at the date.
"One day after the incident."
Kang nodded.
"And the same day my father apparently left something for me."
He looked at her.
"The envelope."
"Yes."
They were silent.
Hae-in turned the page again.
There was one final document.
A medical clearance.
JANG YU-RI — NO INJURY.
Date:
18 APRIL 2008.
But beneath it, in handwriting, someone had added:
PATIENT REFUSED SECOND EXAMINATION.
Hae-in stopped.
"Second examination."
Kang read it.
"Why would she need one?"
"Because someone thought she had been exposed to something."
"Chemical?"
"Maybe."
"Radiation?"
"Maybe."
Neither answer satisfied her.
Hae-in looked at the form.
There was a hospital stamp.
Central District Medical Center.
She stood.
"Let's go there."
The hospital had changed names twice since 2008.
The records department was in the basement.
A clerk searched the database.
"Jang Yu-ri."
Nothing.
"Try the old hospital name," Hae-in said.
The clerk did.
Nothing again.
Kang leaned against the desk.
"Maybe the records were transferred."
The clerk frowned.
"Wait."
He opened another system.
"There is a manual archive."
He disappeared.
Ten minutes later he returned with a thin folder.
The first page was blank.
The second contained only a date.
18 APRIL 2008.
No patient name.
No diagnosis.
No physician.
Hae-in turned the page.
A list.
Four names.
Three had been crossed out.
The fourth was—
JANG YU-RI.
Beside her name:
OBSERVATION — 6 HOURS.
Kang looked at Hae-in.
"Six hours."
"Why?"
The clerk shook his head.
"I don't know."
Hae-in continued reading.
There was a note from a doctor.
Patient repeatedly asked whether the door had been closed.
Below it:
Patient claims she heard movement beneath the floor.
Hae-in stopped.
Beneath the floor.
Room beneath Room 08.
She looked at Kang.
The connection was becoming too precise.
Then she saw the next line.
Patient refused to identify who opened the door.
Kang exhaled slowly.
"So Yu-ri knew."
"Yes."
"Then why did she disappear?"
Hae-in turned the page.
There was no answer.
Only a discharge signature.
SEO JIN-WOO.
Kang stared at it.
"Your father signed her out."
Hae-in said nothing.
Her father's signature sat at the bottom of the page.
Clear.
Deliberate.
He had personally removed Jang Yu-ri from the hospital.
And whatever had happened after that—
he had taken responsibility for it.
Back at the station, Hae-in placed the hospital record beside the envelope.
She stared at both.
Her father's note.
Jang Yu-ri's medical record.
The photograph of Room 08.
And the photograph left outside Park Eun-sook's apartment.
Four pieces.
One question.
Why had her father taken Yu-ri?
Kang sat opposite her.
"Open it."
Hae-in looked at him.
"You're the one who told me to be careful."
"I've changed my mind."
"Why?"
"Because your father wrote it for you."
She looked at the envelope.
"That's exactly why I don't trust it."
Kang was quiet.
Then said,
"You think someone else could have written it?"
"No."
"Then what?"
"I think my father knew he might not be able to explain everything himself."
She ran a finger along the edge.
"He left instructions instead."
Kang nodded.
"That sounds like him."
Hae-in looked at him.
"You didn't know him."
"No."
A pause.
"But I know you."
She looked down.
"That's different."
"Yes."
For a moment, neither spoke.
Then Hae-in opened the envelope.
Inside was a single sheet of paper.
No photograph.
No file.
Just handwriting.
Her father's.
Hae-in,
If you are reading this, then you found Room 08.
She stopped.
Kang didn't speak.
She continued.
Do not trust the woman who says she opened the second door.
Hae-in's eyes remained on the page.
Below that:
She did not open it first.
Her grip tightened.
Then:
She opened it because someone had already opened the first.
Kang leaned forward.
"What does that mean?"
Hae-in kept reading.
In 2008, Yu-ri saw what was beneath Room 08.
I believed her.
That was my mistake.
A pause.
Then the final lines:
The room beneath Room 08 is not where they kept people.
It is where they kept records of the people they had already removed.
Hae-in stared at the page.
Kang's expression hardened.
"Records."
She nodded.
"Not people."
"Then why build it?"
"To remember them."
"By whom?"
Hae-in turned the paper over.
Nothing.
Then she noticed a faint impression near the bottom.
She angled it toward the light.
There were words pressed into the paper from another page.
She took a pencil.
Gently.
Sideways.
The letters emerged.
C-18
And underneath:
ARCHIVE SUBLEVEL B
Kang stood.
"The courthouse."
Hae-in folded the letter.
"Yes."
"You think C-18 is there?"
"I think my father wanted me to look there."
Kang reached for his coat.
Hae-in stopped him.
"Not yet."
He looked at her.
"Why?"
She placed the letter beside the photograph.
"Because my father made one thing very clear."
"What?"
"He didn't trust the woman."
Kang waited.
"And neither do I."
That evening, Hae-in returned to Park Eun-sook's apartment alone.
She knocked.
No answer.
She knocked again.
Still nothing.
The door was unlocked.
Hae-in pushed it open.
"Ms. Park?"
Silence.
The apartment was empty.
The blanket was still on the chair.
The cup from the previous day remained on the table.
But Park Eun-sook was gone.
Hae-in stepped inside.
On the table was a folded piece of paper.
She opened it.
Three words.
DON'T GO BELOW.
She looked toward the hallway.
Then toward the window.
Nothing.
Her phone rang.
Unknown number.
She answered.
No greeting.
Only breathing.
Then the distorted voice.
"You opened it."
Hae-in's eyes narrowed.
"Yes."
"You shouldn't have."
"You knew I would."
Silence.
Then:
"I wanted to see what he left you."
Hae-in froze.
"You?"
The voice didn't answer.
Instead, it said:
"Your father didn't leave you the eighteenth."
Hae-in looked at the letter.
"He left you the key to it."
"What is C-18?"
The line went quiet.
"Who are you?"
Nothing.
Then one final sentence.
"Ask your father why he stopped looking."
The call ended.
Hae-in lowered the phone.
She stared at the empty apartment.
Then at the note.
DON'T GO BELOW.
For once, the warning didn't make her want to investigate immediately.
It made her wonder who had written it.
Park Eun-sook?
The woman?
Her father?
Or someone who knew she would find it.
Hae-in folded the note.
She put it beside the letter.
Two warnings.
Two different hands.
And the same instruction.
Don't go below.
She looked at the clock.
Then at the courthouse file number written in her notebook.
C-18.
She closed the notebook.
Tomorrow, they would go to Archive Sublevel B.
But she would not go looking for the room beneath Room 08.
Not yet.
She had learned enough to understand something her father had known years ago.
Sometimes the most dangerous door was not the one hiding the truth.
It was the one someone desperately wanted you to open.