The Mission's Invisible Wall

A message window appeared precisely in the center between Woojin and the entrance to the accident scene.

The moment he saw the text floating inside it, his dazed mind snapped back to attention. Only then did Woojin lower his head to check his own body. He was fully geared up in a complete set of firefighting gear. Just like the... no, it was more accurate to say they'd merged? Anyway, he looked exactly like that enigmatic 'existence' he'd encountered moments ago.

That realization sparked one burning question in his mind.

'Why am I wearing firefighting gear, of all things?'

There had to be a reason he'd ended up on this chaotic, unidentified stretch of highway dressed like this. Woojin glanced past the message window toward the scene. It was a relief that no embers were visible yet, but that also meant...

If there wasn't going to be a fire, why bother with the turnout gear?

'Why does this feel so off?'

An inexplicable unease kept gnawing at him from within. On a multi-vehicle pileup site like this, a fire could break out at any moment without warning. Plus, the fact that Lee Geon-woo's main duties as the protagonist of Burnt and Hidden Marks involved fire suppression only made Woojin's gut twist even more.

He couldn't shake the ominous vibe hinting that a blaze was imminent.

If fire erupted amid the tangled mess of cars on the three-lane road, it would spell absolute catastrophe.

"No way, it won't happen..."

This starting point felt worlds apart from the two virtual worlds he'd experienced before. Maybe that's why the sense of wrongness, starting from the smallest details, hit him so hard.

He prayed it wasn't a bad omen. He desperately hoped it was just needless worry.

Woojin shook his head, trying to shake off the heavy thoughts. Just as he stepped toward the message window and reached for the 'Yes' button that had appeared below the text—

BOOM!

A deafening explosion rocked the air out of nowhere. He nearly tumbled over in shock. Woojin reflexively lowered his raised arm and looked toward the source of the sound.

The sight beyond the message window was a nightmare on top of a nightmare, in a word. The noise had come from an explosion.

A massive pillar of fire shot skyward, followed by thick black smoke billowing furiously, ready to blot out the blue sky.

‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠

"Aaaahhh!"

"Help! Somebody save us!"

"Let me go! My kid's still in there! Please..."

The desperate cries from people in the accident zone grew louder, echoing in his ears like tinnitus.

"Stay back, it's dangerous!"

"Ramp up to 9 kilos once the hoses connect!"

"Move the patient, hurry!"

Firefighters and rescuers were tangled in the chaos, pouring everything into the rescue efforts.

Damn it... Why did his bad premonitions always hit the mark?

Then—

BOOM!

A second explosion followed. This one came from inside the tunnel, behind the first blast site.

LPG cylinders from an overturned truck in the pileup had rolled deep into the wreckage, unnoticed until now, and detonated one after another.

A firefighter's shout jolted Woojin's mind wide awake. Survivors trapped in the tunnel—mostly kids!

"Up to 10 kilos pressure!"

"Get closer, hurry!"

Shouts from firefighters echoed everywhere.

Smoke from the blasts obscured the tunnel interior, but the second explosion likely meant fire had ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠spread to the kindergarten bus inside.

At this rate, mass casualties were inevitable.

"No... no way..."

Forgetting even to hit the 'Yes' button, Woojin vaulted over the message window toward the entrance path.

'Kindergarten bus... I have to save the kids.'

Missions be damned—they weren't even registering. All he could think was saving lives first. His body moved on instinct.

In that instant, another bizarre phenomenon overtook him. Suddenly, specialized knowledge and experience as a firefighter flooded his mind.

It felt like he'd been reborn as Firefighter Lee Geon-woo. This had to be because that 'existence' had passed through his body—merged with him, really. The pain right after made sense now. Nothing else explained it.

He was certain: it wasn't just an encounter; they'd fused.

But then—

Thud!

The moment his foot hit the entrance path, something slammed into him, bouncing him back.

"Wh-what?!"

Flustered, Woojin threw himself at the ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠path again—

Thud!

Same result. An invisible barrier blocked him.

"What the hell! Get out of my way, you fucking—!"

A curse slipped out unbidden. Kids were dying, and he couldn't get through!

"Ah, wait..."

Woojin's eyes flashed. Could it be because he hadn't accepted the mission yet?

"Damn it, this is insane!"

The diary wasn't just unhelpful; it was utterly rigid now. Frustration boiled into rage. Every minute, every second mattered, and his insides burned black with impatience.

Tap-tap-tap.

No choice—he turned back, dashed to the message window, and slammed the 'Yes' button.

The text shifted, and—

Whirr.

The traces of the invisible wall vanished in an instant. Woojin bolted full-tilt toward the scene.

'Huff... huff.'

The heavy, sweltering turnout gear pushed his breath to the limit, but he couldn't stop.

'Hold on...'

Another doubt struck mid-stride. Earlier, the shout had been, "Twenty unable to evacuate from the kindergarten bus inside the tunnel!"

Why did the mission say 21 survivors? Damn, it only gave him a bigger headache.

Focus on what needed doing.

Whoosh!

Up close, the fire was far worse than he'd imagined. Flames roared like a furious fire demon, spewing blistering heat and completely sealing the path to the tunnel.

First priority: extinguish the primary fire that had spread in a straight line along leaked fuel from the wrecked vehicles.

"Keep hosing it down!"

The fire chief bellowed continuously, and the water streams from multiple hoses intensified.

"Hold it!"

"Hang in there—no matter what, we kill it from here to save the survivors!"

Several firefighters braced each hose, enduring the brutal pressure with their bodies as they struggled on.

Woojin rushed over and grabbed a hose.

"Nngh!"

His arms and legs went numb almost immediately, but he bit his lip and held firm. The metallic tang of blood hit his tongue from biting so hard.

Didn't matter. If it meant saving the kids, he'd shatter his body a hundred times over.

As they held longer, the flames weakened somewhat from the initial fury but remained a threat.

"This won't cut it. Demo team, prep to move in—hose team, cover us!"

Judging no more time could be wasted, the chief ordered the demolition team forward.

"Lee Geon-woo! You're on point!"

The chief pointed at Woojin and shouted.

Ah, so it wasn't just a feeling—he was really Lee Geon-woo.

"Y-yes, sir!"

Dropping the hose, Woojin grabbed a fire axe and charged left around the flames. The lone refrigerated truck amid the inferno was the only spot not fully engulfed.

With his trailing teammates, he started smashing the crumpled driver's door blocking the path. Chainsaws, axes, hammers—every tool in the arsenal.

Bang-bang-bang!

Through the opposite window, the tunnel entrance loomed. Break this door, pass through the truck cab, and they'd be in.

His turnout gear was soaked with sweat inside, but 'Come on, just a bit more!' Woojin kept swinging relentlessly.

Once, twice, three times... Like a man possessed, he hammered away nonstop, visions of the kids' bright smiles flashing before him amid cries of 'Rip open, damn it! Please!'

Smiles he absolutely couldn't let slip away. He had to reclaim them!

Crack!

"It's open!"

Heaven didn't ignore his desperate plea. The obstacle blocking the only path to the bus was breached.

But the situation remained hopeless. Smoke and flames from the shattered door mocked their efforts, blocking visibility.

"Path cleared!"

"Hold position. Hose team, concentrate on that side."

Woojin radioed the chief immediately, who ordered them to wait.

"Wait? We need to go now—"

—Who doesn't know that? Secure safety first, then we move! Stand by!

The chief snapped back in a heated tone.

Everything had procedures and order. Even in emergencies, as chief, ensuring team safety was paramount— one team member's life equaled multiple survivors' lives.

Woojin acknowledged it as the best call. Rationally, yes. But his heart...

"Sorry, sir."

—What?!

"I'm going in now."

"Hey, Lee Geon-woo! You crazy bastard!"

Before his teammates stomping behind him could stop him—

Hiss.

Woojin shoved into the truck cab, still thick with smoke and embers. Not a hint of hesitation.

"Argh!"

Residual moisture in the truck turned to scalding steam in the hot air, raining down on his gear.

When he'd first read the Burnt and Hidden Marks script, he'd looked up firefighter interviews. Even in turnout gear, burns were inevitable. He'd thought, 'Eh, but it's fire gear.' Naive bullshit. It was real.

No need to check; he felt the burn on his back, arms, even the nape of his neck.

Still, Woojin shoved the pain aside with urgency and crawled out the passenger door. That brief passage felt eternally long.

"Hah."

Panting raggedly, he hauled himself up and moved without pause. Less than 10 seconds later—

Boom!

The truck's right-side vehicle exploded. The hard-won path sealed shut again. A few more seconds' delay, and he wouldn't have even glimpsed the bus...

Fire scenes were a razor-edge thrill ride, every step a line between life and death. Sweat-drenched already, a chill still ran down his spine.

—Lee Geon-woo! Respond!

The chief's frantic voice crackled over the radio.

—You better not be dead! Answer me!

Tremors shook the urgent demand.

"...Made it through safely."

—You suicidal idiot... You know you just dipped your toes in the River Jordan?

A string of curses flew ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠over the radio, but the chief sounded relieved.

—When you get back, it's report-writing duty first...

"Sorry for worrying you. I'll take the chewing out later."

—...Just stay alive, you punk! What's the situation there?

The tunnel loomed about 50 meters ahead.

"No major flames visible, but heavy smoke pouring from the entrance."

Fire was bad, but toxic gas was the real killer. How long could exposed kids last?

"Entering for search now."

—Move carefully. Keep reporting.

"Got it."

—One more thing, Lee Geon-woo. Your safety matters too. Your life is their lives—got it?

"Yes, sir! Heading into the tunnel!"

Woojin shouted into the radio and sprinted for the entrance. His body, encased in 25kg of gear amid 40°C+ heat, felt leaden and battered.

Yet what drove him was

those three words: 'survivors.' And the solemn duty as a firefighter to turn that '0' into '21.'

Nothing else.