Dangerous Heartbeats

The final mission is drawing to a close.

Soon, this life spent wearing a sickening mask, this existence of dodging death and racing against the clock, will finally be over.

No more bleeding, no more staining my hands with the copper stench of blood.

No more running until my lungs feel like they are about to burst from the sheer pressure.

Clinging to that single, fragile thread of hope, I push the heavy door open. A rich, unfamiliar scent rolls over me, carrying the crisp, warm air of a world entirely different from the dark underbelly I have endured.

Whether I succeed and taste a brand-new life, or fail and die as a perpetual liar—either way, it all ends tonight.

The final mission I have yearned for, over and over, is about to begin.

= = =

One year ago, on the final, freezing night of February.

A dark silhouette drifted through the pitch-black forest like a phantom slipping through the shadows.

With a slender frame and deceptively small stature, the silhouette was hard to take for an adult man, but her movements were as lethal and agile as an apex predator that had tamed the mountain itself.

'It is almost over. So why do I feel so damn uneasy?'

Already breathless, Hyeon-sin felt suffocated by the chest binder strapped brutally tight around her ribcage.

In intense moments like this, her own feminine body felt like nothing but a beautiful nuisance. Having to masquerade as a man at all times, her breasts—constantly trying to assert their presence through the thick compression bandages—made dressing an absolute nightmare.

While Hyeon-sin poured everything into mastering the brutal art of bringing a man to his knees, she had never neglected the savage conditioning required to protect and endure.

To execute missions as a female operative, she could slip into various disguises using her natural charms, but her recent stint undercover as a nurse had been pure, agonizing hell. In the end, she preferred this—breaking through complications with raw, physical force.

The distinct presence of several pursuers echoed from dozens of meters behind her. The mountain terrain was treacherous. No doubt, they were suffering too.

Still, the days Hyeon-sin had spent scouting this territory had not gone to waste.

Running through the dark meant slipping was a constant threat, but a body subjected to ruthless training since childhood always proved its worth in crises like this.

'Finally.'

As she sprinted onto the dirt path, she repeatedly pressed the bike’s smart key. Beep, beep—a welcoming chirp pierced the distance. The motorcycle, concealed beneath a black tarp and broken branches by the roadside days ago, had blended seamlessly into nature.

A wave of relief and crushing exhaustion hit her all at once. Her breath caught in the back of her throat, her fingertips tingled with frantic adrenaline, and her throat burned with a raw sting, but she skillfully kicked the powerful engine to life.

Her body screamed in agonizing protest. Breathing through the heavy tactical mask felt like slow torture, but fueled by a sudden surge of hope, she cranked the throttle.

A sharp, exhilarating roar sliced through the stillness of the night as the bike tore up the incline.

The desperate shouts of her pursuers faded into the distance. The moment she transitioned from the dirt trail onto the smooth asphalt—the shortest route out—she finally let out a long breath of relief.

The bike’s speed surged, its thunderous roar amplified by the dead of night. Adrenaline flooded Hyeon-sin's veins, matching the violent tempo of the speed and sound.

'I have got plenty of time.'

Thank god for small mercies.

= = =

It wasn't until she reached the massive high-rise at the designated coordinates and pressed the elevator button that Hyeon-sin truly exhaled.

If anyone were to look at the elevator CCTV right now, they would see a highly suspicious boy in combat gear, short hair, and a black mask.

'Ha.'

Inside the mirror, Hyeon-sin—an operative of the KSD (Korean Secret Organization) who lived in the shadows for the sake of justice—smiled at her own reflection.

Though she was a fully grown woman in her twenties, circumstances forbade her from revealing her true identity. Consequently, she kept her hair cropped short and always dressed like a male student.

Her reflection bore the undeniable exhaustion of crawling through the wilderness, but her expression remained bright; the thought of wrapping up the mission made her feel weightless.

[Mission: Deliver the USB containing evidence of medical corruption to the client. Payout: 20 million won.]

Recalling the brief, she found herself anticipating the meeting that lay just moments away.

Once she handed over the data stored in the USB inside her pocket, her duty would be successfully fulfilled.

The mere thought of downing a quiet drink and stretching her bare legs in some comfortable motel room tonight brought a natural curve to her hidden lips.

Rich people certainly seemed to love high places. Through the glass elevator walls, the quiet nightscape of Seoul unfurled like a painted canvas, bidding a poetic farewell to the end of February. When the elevator finally ground to a halt after a long ascent, she strode directly toward the office agreed upon with the client.

Even the hallway was heavily carpeted, muffling her footsteps.

As expected of an office occupied by an insanely wealthy client, the building bled luxury and silent power from every corner.

Knock, knock.

She tapped lightly on the door. One second, two seconds of dead silence stretched, amplifying her heartbeat.

And then, in that very instant—

"Time's over."

A cold, dangerously smooth young male voice drifted from inside the office, causing Hyeon-sin’s entire body to instantly freeze.

Did the client change?

Slowly pushing the door open, a vast, dark office revealed itself before her eyes.

The room was completely devoid of artificial light, illuminated only by the cold moonlight filtering through the windows and the distant neon glow of the city grid. Standing tall, she took confident strides toward the client's desk, keeping her eyes locked on the man ahead, assessing him with every step.

The man in his sixties who was supposed to be there was gone. Instead, a young man, seemingly in his mid-to-late twenties, stood to greet her.

As he rose, a colossal shadow stretched across the room. He radiated a suffocating, dominant tension, moving like an apex predator at the top of the jungle pyramid, slowly closing in on its prey.

Dressed in a sharp, tailored suit, the young man exuded an overwhelming, crushing dominance with every step he took through the dark.

Behind him, the massive floor-to-ceiling windows framed the night lights, casting a faint, ethereal glow around his broad shoulders as if the city itself were offering its blessing.

Even in the dim silhouette, Hyeon-sin could discern his striking, sharply defined features—the thick brows, the high bridge of his nose, the immaculate, dangerous structure of a devastatingly handsome man.

Had things gone sideways, or had she walked straight into a trap from the very beginning?

A hollow sigh escaped Hyeon-sin’s lips. The man’s murderous aura was so absolute it felt as if it could freeze her breath, sending a visceral, hot chill straight down her spine.

The crushing realization that a whole week of blood and sweat had been entirely in vain made her want to drop to her knees.

"Tsk. Miserably slow."

At his mocking, low murmur, Hyeon-sin immediately checked her watch. She was by no means late for the appointment time agreed upon with the client.

"Who are you?"

She genuinely needed to know who the hell he was.

As he stepped closer, every survival instinct she possessed screamed that this man was pure danger.