The train's wheels sang a low, metallic hum against the tracks, the sound rolling endlessly into the dim tunnel ahead. Outside the windows, the last trace of daylight had long been swallowed by the darkness, and yet there was no sense of claustrophobia. The air inside the cabin felt different. Thicker. As if they had already left behind the familiar breath of the world they knew.
They didn't notice the change at first.
It began with the light. The usual flicker of overhead lamps shifted into a faint, pale-gold glow, casting warm, surreal shadows over their faces. Then came the distant shimmer beyond the glass, like threads of silver weaving through the dark.
Someone leaned forward in their seat, forehead pressing lightly to the cold glass.
"…What is that?" a boy whispered, eyes narrowing as the threads became more defined—like rivers of light winding through an unseen landscape.
No one answered.
The humdrums ordinary folk who would never step foot here would have called it an optical illusion. A trick of the mind after too much tunnel and too little sky. But every passenger in this compartment felt it: that quiet, magnetic pull, the way their chests tightened as though they'd crossed a threshold they could never uncross.
Then, without warning, the darkness opened.
The tunnel walls fell away, replaced by an expanse so vast it defied sense.
Beyond the glass sprawled a city not above ground, but suspended within an enormous hollow chamber carved into the bones of the earth itself. Entire districts floated on great platforms tethered by gleaming chains, connected by bridges that shimmered like threads of starlight. Towering spires reached for a ceiling lost to shadows, where clusters of glowing crystals pulsed like distant constellations. Somewhere far below, faint rivers of molten gold flowed, casting light upward into the suspended cityscape.
No one moved. No one breathed.
A girl sitting near the aisle gripped the edge of her seat, knuckles white. "This… this isn't real."
A quiet laugh broke the silence.
When they turned, a man stood in the aisle tall, sharply dressed in a deep navy conductor's uniform that seemed a little too pristine for the sooty tunnels. His cap shadowed his eyes, but his smile was a curve of practiced ease.
"I assure you," he said, voice low and even, "it's real enough."
The group exchanged glances. They hadn't even heard him approach.
"You're the conductor?" one asked cautiously.
"Leo," he replied with a faint bow. "Conductor of the Interlink Express. And your first guide into the Hidden City."
Hidden City. The words felt heavy, like they didn't belong in casual conversation.
"What is this place?" another boy asked, leaning forward, voice half-wary, half-curious.
Leo's eyes glinted under the brim of his cap. "A society that humdrums" he glanced meaningfully at them "are not permitted to see. For good reason."
Someone scoffed softly. "That's vague."
"It's meant to be." Leo's smile didn't falter, but there was a sharpness to it now. "Questions are welcome. Answers… come in their own time."
"You sound like you enjoy being cryptic," a girl muttered.
"Enjoy? No. But suspense keeps you awake." He leaned against a nearby seat, his presence oddly unintrusive despite the fact that every eye was on him. "And you'll need to be awake for what's coming."
"What is coming?"
"You'll see when we arrive," he said simply.
The remark earned a collective groan from a few in the group, but there was a flicker of amusement in Leo's expression, like he'd been expecting it.
After a few more exchanged questions half of which were deflected with infuriatingly calm half-answers Leo finally straightened.
"It's time," he said. "We'll be connecting with the other pods shortly."
At that cue, the far side of the compartment hummed, and a partition slid away to reveal another connected cabin. Inside sat nine more passengers five boys, four girls each distinct in presence. One boy had hair as pale as ash, dressed in a sharp black coat; another lounged carelessly with his hands behind his head, boots tapping against the floor in restless rhythm. A girl with cropped hair and a fierce gaze sat with arms crossed, while another clutched a worn leather notebook to her chest.
No names were exchanged, but glances were. Subtle assessments. Quick, silent calculations of who might be an ally or a rival.
The train began to descend.
It wasn't like an elevator, not quite. More like the world around them was tilting, folding inward, lowering them into the belly of the Hidden City.
The closer they drew, the more details revealed themselves: balconies strung with glowing vines, airships drifting between the spires, a faint, echoing hum that seemed to come from the city itself. Somewhere in the depths, machinery churned a heartbeat of gears and steam.
Finally, the train glided into the station.
Three figures stood waiting at the platform. One was a tall, broad-shouldered man in dark military dress General Vasileious whose presence alone seemed to demand silence. Flanking him were two others in crisp white lab coats: a lean, dark-haired man with sharp features Dr. Ruan and a fair-haired, bespectacled figure whose eyes scanned the group with precise calculation Head Professor Darien.
As the doors hissed open, the General stepped forward first. His voice was deep, resonant.
"Welcome to the Hidden City," he said. "Follow."
No room for negotiation.
They fell into step as Head Professor Darien began to speak not to answer questions, but to brief. His words were carefully measured, as though each one had been weighed before it left his mouth. Something about initial processing, orientation schedules, protocols they would be required to follow. Not a single detail about why they were here.
Still, curiosity tugged at them. Some listened intently, filing away every phrase. Others let their gazes drift drawn to the vast expanse of the station itself.
The ceiling soared impossibly high, veined with glowing crystal lines like the roots of some colossal tree. Archways of obsidian and steel curved elegantly overhead, while platforms extended in layered tiers, each bustling with workers in uniforms and travelers in clothes unlike anything aboveground. The air smelled faintly of ozone and oil, carrying the muted clatter of distant machinery.
One boy brushed his fingers against the rail as they passed, marveling at the faint pulse of warmth under the metal. A girl tilted her head to catch snippets of a foreign dialect from two workers loading crates. Somewhere overhead, a mechanical bird darted past, wings glinting like hammered silver.
They weren't just entering another place.
They were entering another world.