The City's Hidden Heart

In the deepest parts of an old city, rumors circulate about a forgotten passage. Officially, it was an underground utility passage permanently closed in the late 1970s due to structural instability and toxic gas leaks. However, on internet communities and the worn walls of neighborhood pubs, a different story was written: ‘someone’ was still ‘working’ inside, and faint light and strange murmuring sounds leaked from behind the sealed door. Witness accounts of curious individuals attempting to enter and disappearing without a trace were too vivid to dismiss as mere urban legends.

After years of collecting and documenting such stories, I finally decided to verify the source of the rumors myself. I managed to obtain old construction blueprints and located the sealed entrance. The rusted iron door was tightly shut, but the cold air seeping through the gaps was unlike that of a simple underground space. An oppressive, quiet silence overwhelmed me. Using tools, I opened the door, and air mixed with the pungent smell of mold, wet earth, and an unexplainable metallic, fishy odor wafted out.

Relying on the flashlight's beam, I stepped into the darkness. The passage, stretching long along the walls, was filled with traces of moisture and time. How deep had I gone? Suddenly, a very faint vibration could be felt from a distance. Thump, thump, thump. At first, I thought it was my imagination. But after a few more steps, the sound became clearer. It sounded like a broken machine, or perhaps something enormous pulsating.

I quickened my pace, searching for the source of the sound. Exiting the narrow passage, a wide space hidden deep underground appeared. The air grew colder, and the ‘thump, thump’ vibration now resonated through my entire body. A strange blue light dimly flickered along the walls. As I cautiously approached, the light seemed to contract and expand rhythmically.

Finally, I reached the source of the light. My heart sank to my feet. It wasn't an old generator or a faulty lamp. In the center of a massive wall, amidst a tangle of countless pipes and steel structures, something was pulsating as if alive. Sticky, dark liquid flowed along pipelines, as if the organ of a gigantic creature had been forcibly implanted, and irregular blue light burst from its core.

Holding my flashlight, I moved closer. The sound of liquid flowing, the ‘thump’ vibration, no longer felt like my own. Fixed to the wall, emitting light, it changed its rhythm as if observing me. Suddenly, from the center where the light was emanating, a long shadow stretched out. It wasn't a shadow. It didn't appear opposite the light; rather, something long and slender extended from the light itself, attempting to brush against my feet. The flashlight beam remained steady, but what moved in the darkness seemed to possess an independent will. My breath caught in my throat.

Instinctively, I recoiled. The thought that I should not stay there any longer dominated my mind. I turned and ran desperately. Scraped and bruised in the narrow passage, my only thought was survival. The ‘thump, thump’ sound from underground merged with my heartbeat, shaking my entire body.

When I finally crawled back to the surface, the city's noise and light no longer felt ordinary. What I had encountered was an unexplainable entity hidden within the city's old structures. Since that day, in the stillness of the night, I often hear the thump, thump, thump sound reverberating from deep underground. And I am seized by the certainty that somewhere in a sealed space, that strange blue light is still pulsating.