Part 1: TheInvisible Entrance
We left the supply post at dawn. The sky hadn't fully broken—clouds still hung heavy like slabs of stone suspended overhead. The air smelled of damp earth, kitchen smoke lingering from the night before, mingling with fog into a cold, thin mist stretching down the hillside.
I walked in the middle of the formation—behind Lâm, ahead of Thành. Our squad was deployed to Tân Hòa—a stretch of lowland forest near the plains, where the tunnel system branched out like a termite nest, and our underground network had stayed hidden for years. Our mission: rotate in with the combat engineers and hold the underground defense post.
Sounds simple.
But anyone who's ever crawled into a tunnel knows—it's not for the faint of heart.
We arrived by early afternoon, bodies aching, uniforms crusted with dust and sweat. The tunnel post lay tucked in a shallow valley, cleverly disguised with straw and brush. The main entrance was nothing more than a hollow beneath a bamboo root, covered with a thin wooden panel smeared with dirt to match the ground.
Waiting for us was a mid-rank lieutenant, skin dark, lips thick, speaking in a heavy Northern accent:
"I'm Cường, commander of Tunnel Post 5. Just call me Brother Cường—it's easier."
Then he shook hands with each of us:
"Welcome, comrades. I'm sure there'll be plenty here… to remember for life."
I wasn't sure if he meant it as a joke—or a warning.
After a short rest and a meal of corn rice and dried fish, we were given a "tour" of the tunnel system.
The entrance was narrow. We had to crawl in on our stomachs. The earth was cold and damp, reeking of mildew, laced with the faint scent of old blood and gunpowder. I felt as though I were crawling into the belly of some long-dead beast.
Inside branched out into narrow veins. Some passages rose to a meter high, others barely wide enough to squeeze through. Some sections were pitch black—even with a flashlight.
Cường explained:
"Each path leads to a different substation: the infirmary, food stores, meeting room, sleeping quarters, booby traps, and so on."
"Booby traps?" Thành asked.
"Yeah. If the enemy gets in, trust me—you don't want to be the first one through."
We fell silent.
That night, we were assigned to sleep in a side chamber. "Sleep" was a generous word. Underground, the damp clung to our chests, our breathing echoed double, and every movement bumped up against the cool earth walls.
I lay next to Thành, our backs turned toward each other. Lâm was at the far end, his rifle propped against his back, snoring softly.
I couldn't sleep.
Partly because of the overpowering smell of soil.
Partly because every time I shut my eyes, I saw the same dream—the one where Trung stood in the forest, holding a snapped rifle, calling me in a hollow voice:
"It's too dark here, Tính…"
The next morning, I met the person who would change everything about my time in this war.
Her name was Hiền.
She was the only medic still stationed in Tunnel Post 5.
Hiền was petite, hair tied neatly with a frayed string, dressed in a faded gray áo bà ba, wearing old rubber sandals. Her face wasn't beautiful, but it had a kind of stillness. She spoke little. Just nodded when greeted, handed out the right dose of medicine, and never complained.
I'd scraped my leg on a wall—blood had soaked through the bandage. At the underground infirmary, Hiền crouched down silently and cleaned the wound. Her hands were cold but steady. Not a single small talk question. Only the faint smell of alcohol… and earth.
I sat still, barely breathing. Felt like even the smallest movement might shatter the delicate silence blanketing that space.
"All done. Don't get it wet," she said.
I nodded. Then blurted out:
"How long have you been here?"
She didn't answer right away. She folded the gauze neatly, then replied:
"Since the first explosion outside the tunnel entrance."
I didn't ask anything else.
That night, I lay on the damp earth, restless.
In my head was the image of Hiền at dusk: sitting alone, lighting an oil lamp, writing something in a notebook. The golden light flickered across her cheek, casting shadows like ink stains spreading across the wall.
I didn't know why I thought of her so much.
Maybe because she was the only person who seemed calm in this place full of sweat and breath.
Maybe... because I was starting to feel afraid.
And in this darkness, anyone with a face that still held peace… became a light I could cling to.
Three days later, something happened that none of us would forget.
A new group of soldiers arrived from another region. Among them was a man named Tú—tall, gaunt face, quick eyes, hands that trembled slightly every time he drew his gun. When he met me, he asked:
"What's your name?"
"Tính."
"Not the Tính from Bo Gai Hill, right?"
I froze.
"Yeah. How do you know?"
Tú didn't answer. Just gave a faint smile and walked away.
That night, Lâm whispered to me:
"That guy's not right. I heard he was involved in a 'thing' back at base—someone gave the wrong enemy position and two squads were wiped. He was suspected. But they had no proof."
I looked out the tunnel entrance.
Stars flickered like cat eyes.
And I felt a chill crawl down my spine.
Part 2: The Ninth Chamber No One Enters
The tunnel system of Post 5 had eight main chambers. Each was marked with a Latin letter from A to H—corresponding to different functions: logistics, infirmary, meetings, food storage, sleeping quarters, traps, communication, and emergency exits.
But I soon discovered a ninth path—nameless, unmarked.
Just a crack in the earthen wall, barely wide enough for one person to crawl through.
I stumbled upon it while hugging the wall to avoid a collapsing trap.
I told Lâm. He frowned.
"I thought there were only eight? I've never seen anything branch off from here."
We shone our flashlights inside. A narrow path stretched into darkness, the soil clumped, with faint indentations—like someone had once walked that way… and never returned.
I didn't go in right away.
But something took root in my mind—a creeping sense, like a rogue root branching out inside my thoughts, growing a little more each night.
That path wasn't on any map.
No one mentioned it.
It had no name, no function.
And maybe that's why it existed more vividly than the others.
It became a secret—one only I knew.
And as with all secrets in war—it festered like a tumor.
Three days later, something strange happened.
Tú—the new soldier who'd asked me about Bo Gai Hill—reported to command that a crate of ammunition had gone missing. Not fully gone, but moved.
When checked, the crate of mortar shells had indeed shifted by more than 30 cm. The seal was still intact, but there were small fingernail marks on the edge.
Command called for an internal investigation.
Lieutenant Cường looked over each face carefully.
"Who touched the storage without authorization?"
No one stepped forward.
I glanced at Tú. He didn't blink. His face was calm—almost too calm.
That night, I didn't sleep.
I crawled back toward the ninth path.
I took out my knife and gently wedged it into the wall—just a small mark, in case I had to retreat.
Then I crawled in.
Slowly. Handspan by handspan.
The tunnel extended farther than I'd expected.
The smell of the earth changed—now mixed with smoke, damp, and something coppery.
I slowed my breathing, trying not to make a sound.
After a while, I stopped.
My flashlight flickered across a void beneath the ground.
Roughly three square meters.
There were objects—blankets, sacks, a tin box.
I moved closer.
It was a makeshift hideout.
Not built by our side.
I found a Zippo lighter. A worn leather pouch. A small notebook with a torn cover.
I opened it.
The first line made my blood run cold:
"Note on the 17th. Maybe tonight they won't notice. Must move the goods. At any cost."
I brought the notebook out. Sealed it in plastic, tucked it into the inner pocket of my shirt.
The next morning, I pulled Lâm aside and told him everything.
He sat silently for a long time.
"You think it's Tú?"
"I'm not sure. But he knew me. Knew what happened at Bo Gai. He might've had contact with my old unit… or might've been the one who leaked the intel back then."
"Are you going to report this?"
"Not yet. I need more proof."
Lâm nodded, eyes sunken.
"If you keep digging, I'm with you. But be careful. People like him don't just betray once."
Two days later, I returned to the ninth chamber.
This time I brought a dimmed flashlight and my own notebook.
I logged everything—every item, every trace, every line in that old notebook.
There were initials: "H.K."
Even a rough map marking a liaison post near the border.
As I crawled out, I stopped midway—heard a sound behind me.
Someone was following.
I turned off the light. Held still.
The sound stopped too.
The damp earth seeped into my clothes.
My heartbeat pounded like a drum.
I waited.
Then slowly, inch by inch, I backed out.
No one there.
But I knew—someone else knew about the ninth chamber.
And now, they knew I'd been inside.
That night, I stood watch with Lâm.
A light drizzle fell, the sound of water threading through the soil above—like quiet sighs leaking through the tunnel walls.
Lâm handed me a cigarette. I didn't take it.
"I think I'll talk to Hiền tomorrow," I said.
"Ask her to keep the notebook."
"Why?"
"Because if I disappear… at least someone will have the evidence."
The next morning, I brought the notebook to the infirmary.
Hiền was washing her hands with lime water, blood stains still on her áo bà ba.
She looked at me, and asked:
"Something wrong?"
I handed her the notebook, and whispered:
"If I don't come back, burn this. But read it first. Once. And tell no one."
She didn't ask why.
Didn't protest.
Just nodded.
I turned away.
Didn't dare look back.
Part 3: The Scent of Blood Beneath Sealed Earth
That afternoon, it rained hard.
Water slithered down from the hillside, seeped into the tunnel, and turned the soil into cold sludge. We spent the day scooping it out with helmets, emptying buckets until our arms ached.
By nightfall, everything smelled of damp: our hair, our uniforms, even the bullets we carried.
The tunnel felt more like a grave than a shelter.
That was when it happened.
A muffled shout echoed from the food storage chamber.
Then came the sound of something heavy being dragged.
Lâm and I rushed over. Tú stood frozen in the middle of the chamber, eyes wild, his boots soaked in a dark puddle.
At his feet was a body—one of the guards, Nam—throat slit.
Blood had pooled around his neck, mixing with the rainwater into a sticky black film.
Tú said nothing. Just looked at us.
Then bolted.
We chased him through the tunnel.
Flashlights flickered, footsteps splashed through the mud.
Tú turned sharply—down the western fork, toward the ventilation path.
"He's trying to escape!" Lâm shouted.
We gained on him. Just as he reached the old emergency hatch, Lâm tackled him from behind.
They tumbled.
Fists, boots, curses.
I joined in, helped pin him down.
But Tú didn't scream. Didn't plead.
He just kept laughing—low, hoarse, like dirt being shoveled into a coffin.
Lieutenant Cường arrived soon after.
He looked at the blood, then at Tú, then at us.
We told him everything.
About the ninth chamber.
The notebook.
The suspicions.
Cường didn't speak.
Then finally, quietly:
"We'll send him back to central command for interrogation. You two… say nothing to the others. For morale."
We nodded.
That night, the tunnel was silent.
Even the insects held their breath.
The next morning, Tú was gone.
No one saw the transport. No one saw who took him.
Only the drag marks on the floor remained—half erased by boots.
Nam was buried in a shallow grave near the northern wall.
Wrapped in a tarp, marked with a wooden stake.
The third death I'd seen this year.
But the first where I wasn't sure the war was the cause.
That evening, I returned to the infirmary.
Hiền was boiling water in an old kettle, hands stained with iodine.
When she saw me, she simply asked:
"Did you come to take the notebook back?"
"No. Keep it. I just wanted to say… thank you."
She nodded. Then sat down, her back to the wall, eyes half-closed.
"War makes men mad," she said softly.
"Down here, under this much earth, madness echoes louder than gunfire."
I didn't know how to respond.
So I sat beside her.
In silence.
And for a moment, the war felt far away.
Only the scent of boiled herbs and burnt candlewick remained.
But deep in the walls—behind the silent clay—something else had awakened.
The scent of blood.
And it doesn't fade easily beneath sealed earth.
Part 4: The Couriers Who Never Returned
After Tú's death, the tunnel shifted into a new state of vigilance.
Lieutenant Cường ordered a full inspection of every side tunnel, reinforced the traps, and revised the guard schedules down to the hour.
But what haunted us most wasn't that the traitor had died—
It was his final words:
"I wasn't the last…"
One week later, we lost contact with the third courier team.
Three men.
Hoàng—from Quảng Bình, tall, thin, soft-spoken.
Quân—quiet, single-lidded eyes, always the one to lead when cutting through forest.
And Dậu—the youngest, barely two months in the unit.
Their mission was to deliver communication logs and supply maps to Tunnel Station 4, across three hills and a scorched meadow.
The trip should have taken 48 hours.
But four days passed.
No sign.
No signal.
The underground comm line stayed silent.
I felt a chill in my spine.
Lieutenant Cường summoned me and Lâm.
He asked bluntly:
"Do you think they were intercepted?"
I nodded.
"It's possible. The enemy still has informants embedded in this region. After what happened with Tú, I believe he wasn't acting alone. He was the hand—but there's someone pulling the strings."
"Where would that person be?"
"Either near Station 4… or inside the courier team itself."
The air thickened. Lâm exhaled smoke, eyes fixed on the tunnel ceiling laced with roots.
"What now?"
Cường thought for a moment, then said:
"I want you two to go. Tonight.
Carry fake documents.
If someone's watching—we'll know."
We set out at 3 a.m.
A faint beam of light trailed through the jungle's belly.
The path was sludge, swallowing our boots.
A misty drizzle fell, insects buzzed in fits and starts.
The forest felt compressed, like it was holding its breath.
We didn't talk. Just walked.
Each step through the mud felt like stepping across a memory—
where blood and faces had long since merged.
Around 5 a.m., we stopped at a grassy knoll—once a known relay point.
I used the binoculars.
Nothing moved.
But Lâm noticed something.
He pointed to a dense patch of brush:
"Someone was lying there. Grass is still flattened."
I moved in.
Beneath the wild leaves was a fresh boot print—not one issued to our troops.
I knelt.
Caught the scent of American gun oil.
We retreated immediately.
The path back was watched.
We had to skirt along a riverbank—slick, treacherous.
At one point, I slipped, hit a rock, and sliced my arm deep to the bone.
Lâm dragged me up, tied the wound tight with a bloodied rag.
We returned to the station close to noon.
As soon as I reached the entrance, I blacked out.
I woke up in the infirmary.
Hiền was wiping my forehead with a cool cloth.
Her hands were trembling—first time I'd seen that.
"How bad?" I rasped.
"You lost a lot of blood. But you'll live."
I struggled to sit up.
"Any news from the couriers?"
She hesitated.
Then said:
"There's a report from Station 4.
They found three strange bodies hanging from a tree outside the station.
No uniforms. Burned hands. Can't be identified."
My grip tightened on the edge of the bed.
Lâm stepped in, his voice heavy:
"It's probably them."
I bowed my head.
The air in the room shrank into itself.
Three men gone.
No names.
No belongings.
No one left to speak for them.
That evening, I carved three short lines into a piece of wood with my knife.
Wrapped it in cloth.
Buried it near the emergency exit shaft.
No one saw me do it.
No one needed to.
I just needed them to be remembered.
Later that night, Lâm asked me:
"Do you think that was the last traitor?"
I shook my head.
"I think there's more. Not here, maybe. But somewhere we haven't looked yet."
Lâm asked:
"So when does it end?"
I replied:
"When the last man in this tunnel stops suspecting the rest."
Part 5: A Journal With No One Left to Write
After the courier team's deaths, the tunnel system shrank in on itself.
Side shafts were partially sealed.
Missions grew shorter.
Those of us who remained lived like the last few breaths inside a dying lung.
I began keeping a journal.
Not to remember.
Not to preserve anything profound.
But simply so I wouldn't forget what my own words looked like.
On the first page, I wrote:
"If one day I die and no one comes for the body, this will be what's left of me."
I don't know why I wrote that.
Maybe because I'd seen too many people vanish.
No names.
No stories.
No one left to say they were ever here.
Just like the story I'd once heard about a soldier named Sơn—
who'd been stationed at Tunnel 3 and went missing after a bombing run.
Two years later, they found his collapsed hideout.
In the dirt: a skeleton and a rotting notebook, barely legible.
One sentence remained:
"I can hear my own heart breathing. Is anyone else listening?"
I don't know if that line was real or just another ghost story.
But it haunted me for days.
I often sat with Hiền after our guard shifts.
She still didn't talk much, but she had grown used to me.
We never discussed war.
Or politics.
Or death.
Just… little things.
Like the cockroach that crawled into the rice pot that afternoon.
Or how the oil lamp leaned to one side tonight.
I told her about my village, where a long levee snaked through the river bend like a spine.
I talked about my mother—how she saved the last pinch of salt to cook me a bowl of porridge the day I left home.
Hiền listened while her hands kept wrapping bandages, packing herbs.
Sometimes, she'd tell me stories about Bắc Kạn—where she was born.
The mountains.
The mustard leaves.
The cold that cracked her lips.
We didn't love each other.
We didn't dream.
But I knew—
If I survived, I'd find her.
Or at least go see that mountain she once mentioned.
One day, she slipped a folded paper into my hand.
I opened it.
A traced copy of the map from H.K.'s journal—the dead spy's notebook.
Below it, her handwriting:
"I don't believe he had only one book.
He may have passed something along before he died.
I think he was just the third hand.
This chain hasn't snapped yet."
I understood.
And I began staying up more nights.
Watching.
Taking notes.
Comparing maps.
Examining soil layers.
Asking about the past—everyone's past.
Even Lieutenant Cường's.
One evening, Thành—the youngest in our squad—handed me something.
A small black notebook, hidden behind the food storage wall.
"I noticed a stone placed weirdly. Pulled it out, and found this."
I flipped it open.
The first line froze the blood in my fingertips:
"Delivery successful. Recipient: H.T."
Not H.K. anymore.
H.T.
A new name.
A new person.
The next link.
I showed the notebook to Cường.
He said nothing for a long while.
"Could be someone outside the tunnels.
Or… someone still in here."
I said:
"I want to keep it.
Keep digging."
He nodded, slowly.
"Just be careful.
H.T. could be watching you every day."
I went back to my journal.
Turned the page.
"At this point, I no longer know who's a comrade and who's wearing a mask.
But I do know this—
If I die, someone needs to keep writing."
Two nights later, I woke to a sound.
A soft rustling, near the old trap tunnel wall.
I sat up.
Drew my knife.
Turned on my light.
No one.
Only a slip of paper wedged into the rock.
I pulled it out.
Faint purple ink, barely legible:
"Don't dig again.
The next man won't show mercy."
I sat there till morning.
Didn't sleep.
Hiền came in.
Saw me.
Didn't ask.
She handed me a sticky rice ball and a small pouch.
"Eat.
If you're alive, you still walk."
I took it.
Hands trembling slightly.
First time in weeks, I realized I was actually afraid.
Not of dying.
But of dying and no one knowing why.
That night, I wrote the last line in my journal:
"I've begun to suspect even myself.
Not because I'm a traitor.
But because I've lived in the dark so long…
I no longer remember what light feels like."
I closed the journal.
Placed it beside my pillow.
Fell asleep.
For the first time—
No dreams of guns.
Only a golden rice field.
A voice calling faintly in the distance:
"Brother Tính… are you coming home?"
I turned.
Saw no one.
Only a conical hat upside down in the field.
Empty.
.