"This time, we don't chase the attacker," Kang Ji-hoon said calmly.
Han Seo-yeon's pulse was racing.
The train hadn't reached the critical point yet. The pale man at the end of the cabin was still normal. Sitting quietly. Breathing. Not attacking anyone.
Everything looked peaceful.
Too peaceful.
"If it's not him," she whispered, "then what is it?"
Ji-hoon glanced toward the front of the train.
"Listen carefully. Before every explosion, the train shakes differently."
Seo-yeon forced herself to think.
Metal screaming.
Floor vibrating.
A deep impact sound.
Her eyes widened.
"Another train?"
"Possibly."
The announcement began again.
"Attention passengers—"
Static.
Ji-hoon moved first.
"Come."
They pushed through the crowd toward the connecting door.
Passengers complained.
"Hey!"
"Watch it!"
Seo-yeon didn't care.
They needed to see the front.
If another train was colliding—
They had to stop it.
They reached the narrow space between cabins.
Through the small window near the door, Seo-yeon could see the railway tracks curving ahead.
Ji-hoon leaned slightly to look forward.
His expression changed.
Not panic.
Recognition.
"There," he said.
Her stomach dropped.
From the opposite track, another train was approaching.
Fast.
Too fast.
"They're going to crash," she breathed.
"Not yet," Ji-hoon corrected.
The timing was off.
The other train wasn't directly on their track.
It looked close—but not aligned.
Seo-yeon's head hurt.
Then why—
The ground beneath them vibrated again.
Harder this time.
The metal under their feet trembled violently.
"This is earlier than before," Ji-hoon muttered.
Seo-yeon grabbed the emergency handle near the cabin door.
"If we slow down—"
"Do it."
She pulled.
Nothing.
She pulled harder.
An alarm beeped.
Unauthorized.
Ji-hoon stepped forward and slammed his fist against the emergency panel.
"Override access required."
The vibration intensified.
Passengers began screaming from inside the cabin.
"What's happening?"
"Why is it shaking?"
The pale man stood up suddenly.
But this time—
He didn't attack.
He just looked confused.
Seo-yeon's heart skipped.
"So it's not him."
"No," Ji-hoon said. "It never was."
The train screeched loudly.
Metal grinding against metal.
Through the small window, Seo-yeon saw sparks flying near the tracks.
But there was no direct collision.
No second train crashing into them.
Her breathing became uneven.
"Then what is it?!"
Ji-hoon's jaw tightened.
"It's below us."
The vibration became violent.
The floor cracked slightly near the edge of the cabin connection.
Seo-yeon stepped back instinctively.
"An explosion from underneath?" she whispered.
Ji-hoon didn't answer.
Because—
The emergency lights turned red.
The same red.
Every time.
The announcement tried again—
"Emergency protocol acti—"
BOOM.
The explosion didn't come from the front.
It came from beneath.
The force blasted upward.
The cabin floor shattered.
Fire erupted from below like the train had stepped on a landmine.
Seo-yeon felt herself thrown sideways.
The ceiling cracked.
Smoke swallowed everything.
Her last sight—
Ji-hoon grabbing her arm.
And then—
Darkness.
—
She woke up gasping.
Cabin C.
Coffee.
Perfume.
Her body felt heavier.
Her head throbbed sharply this time.
Like pressure building behind her eyes.
The train slowed toward the station.
Ji-hoon was already looking at her.
"Fifth loop," he said.
Her throat was dry.
"It's not a collision."
"No."
"It's not the attacker."
"No."
She swallowed hard.
"It's planted."
He nodded once.
"Yes."
Her chest tightened.
"A bomb?"
"Most likely."
Inside.
Underneath.
Somewhere they hadn't checked.
The pale man sat quietly in his seat.
Normal.
Like nothing was wrong.
Seo-yeon suddenly felt dizzy.
She grabbed the pole to steady herself.
Ji-hoon noticed.
"You're weaker."
She looked at him sharply.
"You too."
A thin line of red slipped from his nose.
He wiped it away before anyone else noticed.
Their eyes met.
Something was changing.
But they didn't have time to think about that.
The announcement began again—
"Attention passengers—"
Seo-yeon inhaled slowly.
"This time," she said, voice steady, "we find the bomb."
Ji-hoon nodded.
"Yes."
The lights flickered.
And this time—
They were ready to search.