The call came at 6:12 a.m.
Seo Hae-in was already awake.
She didn't sleep much anymore.
Not when a case felt… unfinished.
Her phone vibrated once against the glass table.
No ringtone.
No delay.
She picked it up.
"Seo."
"Results came in."
The voice on the other end was the same detective from the apartment.
Tired.
Less certain than before.
She stood.
Already moving.
"Send them," she said.
"They're not… normal."
That made her pause.
Just slightly.
"Nothing about this case is," she replied.
The file arrived seconds later.
She didn't sit.
Didn't make coffee.
Didn't hesitate.
She opened it.
Her eyes moved quickly at first.
Efficient.
Controlled.
Then—
they slowed.
Once.
Twice.
And then they stopped.
Silence filled the room.
Because buried inside the report—
between standard readings, expected traces, routine confirmations—
was something that didn't belong.
Not alcohol.
Not common sedatives.
Something else.
Unlabeled.
Not unidentified—
but unclassified.
Her eyes sharpened.
"Interesting," she murmured.
Because substances don't just appear in reports without names.
Unless—
They're not supposed to be there.
The lab smelled sterile.
Too clean.
Too controlled.
Seo Hae-in walked in without breaking stride.
Black blazer.
Sharp shoulders.
Long skirt cutting clean lines with every step.
The technician didn't greet her immediately.
He was staring at the screen.
Still.
"You called me," she said.
He looked up.
Something uneasy flickering behind his eyes.
"Yes."
A pause.
"I ran it three times."
She didn't respond.
"I thought it was contamination."
"Was it?" she asked.
"No."
Silence.
He turned the monitor toward her.
"This," he said.
Numbers.
Chemical structures.
Data lines.
But one section—
highlighted.
"Doesn't match any standard registry," he continued.
Her gaze didn't move.
"Meaning?"
"It shouldn't exist in his system," he said.
A beat.
"Not legally."
Her expression didn't change.
But something in the air did.
"Effects?" she asked.
The technician hesitated.
"That's the problem."
He clicked to another screen.
"There's no official profile."
Her eyes flickered.
Just once.
"So you don't know what it does."
"I have a theory."
She waited.
He swallowed.
"It suppresses memory formation."
Silence.
But he wasn't finished.
"Not partially," he added.
He turned to face her fully now.
"Completely."
The word settled heavily between them.
"It doesn't blur memory," he said.
"It prevents it from existing."
Seo Hae-in stood still.
Because now—
the gap had a shape.
And shapes meant design.
"Duration?" she asked.
"Unknown."
"Trigger conditions?"
"…unclear."
Her gaze shifted back to the screen.
"Side effects?"
The technician hesitated again.
Then—
quietly—
"There's one thing."
She didn't look at him.
"Say it."
Another pause.
"When combined with high alcohol levels…"
He stopped.
Like he wasn't sure he should continue.
Her voice dropped.
"Finish."
"…it may increase suggestibility."
Silence.
"Define suggestibility."
His voice lowered.
"External influence."
A beat.
"Command response."
The room went still.
Because now—
this wasn't just memory loss.
This was control.
Seo Hae-in stepped away from the screen.
Slowly.
Everything was aligning.
Too neatly.
The missing memory.
The clean crime scene.
The absence of resistance.
And now—
a substance that could erase memory…
and open the mind.
Not break it.
Use it.
"He didn't forget," she said quietly.
The technician didn't respond.
Because he already understood.
"He was made not to remember."
FINAL MOMENT
She picked up her phone.
Dialed once.
The detective answered immediately.
"Tell me you found something," he said.
She didn't waste time.
"There's a foreign compound in his system," she said.
A pause.
"And it doesn't erase memory."
Silence.
Then—
"What does it do?" he asked.
Her eyes darkened slightly.
"It removes the ability to form it," she said.
Another pause.
"That means—"
"Yes," she cut in.
Her voice was colder now.
Sharper.
"It means someone could tell him what to do…"
A beat.
"And he would do it."
Silence.
Heavy.
Unavoidable.
Then she added—
"And never know he did."
END OF CHAPTER 4