When I went to college, my love for the outdoors led me to join the mountaineering club. There, I became close friends with three classmates—A, B, and C (all pseudonyms). Even after graduation, the four of us kept in touch and spent our free time enjoying outdoor adventures together.

One summer, the four of us planned a day trip to hike a somewhat rugged mountain meant for intermediate climbers. It had been a while since our last trek, but we weren't worried, given our past experience. Yet, no matter how experienced you are, nature—and mountains in particular—has a way of throwing unexpected trouble your way.

Everything was going smoothly at first, but the shift was unnervingly sudden. Before we knew it, a thick fog swallowed us whole, transforming our surroundings into a dangerous void where I couldn't even see my fingertips with my arm outstretched. Just as I thought to myself that moving any further was impossible—

"Whoa!"

Someone suddenly yelled out. Then came the sound of something sliding down the slope.

"Hey! Are you okay?!"

We checked our group and realized C was gone. He must have slipped down the incline. We wanted to rescue him immediately, but moving around carelessly in that fog would put the rest of us in danger. We decided to stay put and wait for the fog to clear.

Just how far down had C fallen? We shouted for him repeatedly, but there was no answer. We could only pray he was uninjured...

In the end, the fog didn't lift all night, forcing the three of us to spend the night stranded on the mountain. The weather cleared the next morning, but finding C took priority over continuing the hike. Ultimately, we couldn't locate him on our own and had to head back down to call for a rescue team.

After that, no matter how extensively they searched, C's whereabouts remained a total mystery. When we asked one of the search team members, he told us there wasn't a single trace left behind, as if C had simply vanished into thin air. The slope was steep, sure, but not impossible to navigate; as long as he kept his bearings, C should have been able to make his way back easily. Even the sudden fog was baffling—according to meteorological reports, the weather that day had been consistently clear.

Four years passed. Given the time that had gone by, we had to accept the tragic reality that C was no longer alive. Devastated by shock and guilt, the three of us stayed away from mountains for a long time. But we couldn't stay frozen forever; those of us left behind had to move forward. If we could at least find some sort of clue... Driven by that resolve, we decided to step foot on that fateful mountain once more.

Still, after so many official searches had turned up nothing, there was little reason to think we would fare any better. Despite our desperate efforts, we were useless. Where on earth could C possibly be?

"Hey, what is that?"

As we were taking a break on an open ridge with a clear view, A spoke up. Looking in the direction he pointed, I saw something moving slowly just above the treetops. It was too round and moved too slowly for a bird... Was it a balloon? Deep in the mountains like this? The instant I raised my binoculars to get a better look, all the blood drained from my body, and an uncontrollable trembling took over. I tried desperately to force out words to describe what I was seeing, but my voice failed me. "C... h-h-head... his head..." Once A and B looked for themselves, we all turned deathly pale and stared at each other in silent horror.

It was C—without a doubt. Unbelievable as it sounds, only C's severed head was floating in midair, gliding effortlessly through the sky. His face was blank and hollow, entirely devoid of life. Far beyond being pale, his skin was a complete, dull gray. Was it a ghost, or some kind of monster? Whichever it was, one thing was certain: C was no longer human.

Overcome with terror, searching was the last thing on our minds, and we scrambled back down the mountain. The entire way down, I was terrified that C's floating head would chase after us, but we managed to make it back safely. Between the three of us, we've agreed that what we saw that day was nothing more than a terrible hallucination.

But what did we really see that day? And what on earth actually happened to C...?