A trip into the unknown by anonymous adventurers turned into a journey of apparent terror. Even though they were armed to the teeth, there was nothing to protect them from the horror that lay in wait.

Drawn by an apparent sense of morbid curiosity, the intrepid party peered into the opening – which seemed to beckon them into its inky darkness. Somewhere deep in the woods at a mystery location in the United States, a daring group of explorers slipped one by one into a cramped subterranean tunnel. And amid the menacing shadows, enclosed by cold rock, the very walls appeared to move…

The year of the group’s dark adventure was 2013, but unfortunately next to nothing is known about the individuals: where they came from, who they were or even what they thought they were doing. What little can be verified, though, is thanks to the internet. You see, a brave survivor – known only as “thaturksme” – posted images of the party’s ill-fated expedition on imgur. And the pics seem to document a truly nightmarish encounter.

To some extent, the group appeared to be victims of their own inexperience. For one thing, the foolhardy explorers set out with hardly any essential equipment. Helmets, knee pads, batteries, food, water, ropes, pocket knives and, most essential of all, a first-aid kit were all lacking. In hindsight, then, how could it possibly have gone right?

In fact, the group decided to explore an uncharted cave with little more than a misplaced sense of bravado – and an array of deadly weapons. Their armory included a handgun, a pump-action shotgun and a Colt AR-15 semi-automatic rifle. They also packed a large hunting machete – presumably to save on ammo.

So, evidently sensing that grave dangers lay ahead, the group set out on their journey. And the sense of doom was apparently real: something hideous was lurking in the woods, waiting for them. Something deep underground, hidden from warmth and sunlight in a dank, dark hollow of dirt and rock. And when the time came, those weapons were to be of no use whatsoever.

Even the journey there was far from idyllic. The explorers’ trek led them deep into dense woodland, up and down overgrown hills, across murky streams and through shrouds of tangled thickets. “You seriously could not find this thing unless you knew it was there,” thaturksme wrote on imgur. “The vegetation makes it impossible to see the opening from below, and from above, on the hill, it looks like there’s nothing there.”

Indeed, it was as if a special place of horror had been appointed just for the group. As if the dismal hole in the Earth had yawned open in expectation of this very day and patiently awaited their arrival. In any case, the hour had come. It was time now to descend.

The obscure opening was snarled with tree roots and brambles. Apparently oblivious to what lay ahead, however, the comrades slid their way inside. There, they found themselves enclosed by a narrow tunnel, with corridors branching away into ominous darkness. And darkness – as all young children know – is where monsters and madness reside.

“I had my hands full with my light and my pistol, waiting for the worst,” thaturksme wrote. Caves can, after all, conceal a multitude of hazards. Think everything from dangerous animals to unpleasant diseases – such as histoplasmosis, otherwise known as caver’s disease, which is a fungal lung infection. And according to common wisdom, caves can also be used as dens by violent criminals and as sanctums by Satanists – for twisted rituals and ceremonies.

Still, undeterred, shining his torch, thaturksme saw that the tunnel narrowed until it was about 12 inches high. Obviously, then, it would be impossible for a fully grown human to progress any further along this route. Yet any number of rats, snakes and creepy-crawlies might of course be scuttling around in there.

However, thaturksme couldn’t resist crawling on his belly for a closer look. With his torch now securely attached to the barrel of his rifle, he pointed the light into the hole and peered inside. But nothing jumped out. He saw not a single thing. There was only receding blackness and cold rock.

Thaturksme then decided to explore one of the tunnel branches. After just several feet, however, he came to a dead end. So, he backtracked and tried a second route. But that, too, came to an impassable wall. With the explorers therefore hemmed in by rock, did the cave then begin to feel like a tomb?

Caves are, it’s worth bearing in mind, archetypal symbols of the underworld. In the realm of myth, they represent not only death and hell, but also the vast, unknown reaches of the unconscious mind. It is in the quiet solitude of caves, isolated from the world and society, that hermits, for example, plumb the depths of the human psyche.

But what dark force had drawn the adventurers down here in the first place? And why had they come armed to the teeth? Had, in fact, some deep unconscious urge – dimly sensed and largely unarticulated – lured them into the terror of this virtual void? The father of psychoanalysis, Sigmund Freud, attributed such human impulses to “Thanatos” – the irresistible, instinctual drive towards death.

Then, suddenly, one of the group spotted what appeared to be animal tracks. “My friend said there were paw prints on the ground,” thaturksme wrote. “So I just snapped this picture. I didn’t really see anything.” Indeed, those “prints” may well have been nothing – but, conversely, they might just have been the hellish tracks of some unearthly monster.

Then the party came across bones – animal bones, stripped clean of their flesh. The group had, it seemed, stumbled into some kind of lair – the hideaway of some carnivorous hunter. How chilling to know that creatures had previously been dragged down there dead or dying and then torn to pieces and devoured.

At that point, then, the party wisely decided to turn back. “Shaky hands,” thaturksme explained about this image. And while he was shining his light towards the exit, across the rock walls, something appeared to move. In fact, the entire surface of the rock tunnel apparently seemed to writhe and pulse. What in the name of God was that?

“I had to force myself to look straight ahead,” thaturksme wrote. “Because there were tons of these mutant cricket/spider-looking things just hanging out of the walls, moving around!” And so it had begun: the emergence of “mutant” arachnids surely heralded the group’s terminal slide into insanity!

This must have been when the adventurers realized that their guns were redundant. In fact, guns are arguably relatively useless in any cave; bullets, after all, have a tendency to ricochet unpredictably off walls, and the noise of a shot can itself reverberate violently and damage the inner ear. But in this particular case, the targets were too small and numerous. Better, then, to run – as fast as you can.

Thaturksme and his reportedly shaken friends thankfully managed to escape to freedom. But the moral of this story is that if you go looking for monsters – especially in dank, dark confined places where your imagination is in its element and can truly run free – you are almost bound to find them. And more than this: guns won’t protect you from your own unconscious mind.