Tristan was doing the thing he loved, flying the little utility airhopper over the clints and grikes of the limestone karst near his home. Eagerly he examined the dark fissures, looking for the little creatures that hid from the sun, but also hoping that one day he would stumble on a new cave, maybe even a whole unexplored system.
He had been turning about aimlessly for most of the afternoon when something caught his eye. A deeper black within the shadows. He set the airhopper down on the flat pavement and swiftly dropped down between the zomo bushes, bright with their pale blue flowers, but with razor-sharp thorns. He weaved expertly to avoid becoming snagged.
And there it was, unmistakably. He pulled the lantern off his belt and set it to float mode, then swung his legs over the lip of the crevice and began to ease himself down into the darkness.
His nanosuit kept his body warm, but he felt the chill on his face as soon as he slipped out of the sunlight, and the cold stone felt clammy to the touch. The lantern floating close by his side showed that he was in a passageway that descended steeply. Cautiously he descended. It was slippery underfoot, and he had to look carefully for hand- and footholds.
After about ten metres, the walls of the passage vanished, and he was conscious of entering a much larger space. To his right, a large stalagmite thrust upwards from the wall, and he positioned himself firmly in the angle before adjusting the setting for the lantern.
He sent it out into the void, tracing walls and ceiling, and revealing that he was near the top of a cavern of truly stupendous size, easily dwarfing any cave he had been in before. He sent a command to the lantern to drop slowly down to the floor, and he saw that it was a tangle of rocks and columns. It would not be easy to find a path through them.
The lantern continued its itineration, and Tristan wondered if this was the first light this place had ever seen. As it reached the bottom of the wall below his feet, he saw that he was, at any rate, not the first to discover this place. A large pile of animal bones bore testimony to the sad, lonely deaths of creatures that had stumbled in here since time immemorial and had been unable to climb out again. Tristan gave a shudder, and was grateful he had left the airhopper in a highly visible spot, where it would flag his whereabouts. He looked again at the skeletal remains beneath him, and felt hugely relieved that none of them appeared to be human.
He played the lantern over the cavern wall until he had calculated a route by which he could safely descend, and, more importantly, by which he could return to his present position. When he was satisfied, he brought the lantern back close to him, resumed the float setting, and slowly, cautiously, began to descend. Narrow ledges projecting from the cavern wall facilitated climbing, even though at one point they were crossed by a broad flowstone sheet, which Tristan had to negotiate with the utmost care.
At last he found himself safely on the bottom. He ventured toward the middle of the cavern, and was surprised to discover a stream weaving its way across the floor. He gingerly stepped into its icy water and began following its course, watchful always not to lose his footing.
At the far end of the cavern, concealed by calcium carbonate tumescences of Gargantuan proportions, the stream fed a small lake. The lantern dimly picked out what appeared to be a tunnel in the cavern wall. Conscious all the while that he was probably being foolhardy in the extreme, he waded into the lake.
He was up to his waist before the bottom levelled out. The lantern hovering at his shoulder revealed that the roof of the tunnel was very low. Indeed, he would have to bend until his face was almost in the water to keep from cracking his skull open. He advanced. The lantern accompanied him, it too almost in the water. He edged along the tunnel for some minutes, losing all sense of distance, nearly falling over a large boulder in the bed of the stream, left there by some unstoppable flood in times past. And then the tunnel was behind him.
Again he sent the lantern to explore. This cave was smaller than the last, and less crowded with speliothems. The stream fed another lake, a kind of sump, which occupied most of the cave. Tristan moved to one side of the lake where there emerged a raised area like a kind of natural podium. He pulled himself out and sat, dangling his feet in the water.
And then it was that he became aware of a sound. At first he assumed it was another watercourse somewhere close by, but the sound was not that of rushing water. It was more in the nature of a hiss, and, moreover, it appeared to be coming closer. Tristan’s curiosity metamorphosed into alarm as the volume and intensity of the sound increased.
He jumped to his feet and ran to the wall at the rear of the podium. He placed his hand on the rock. It was vibrating. Struggling to find an explanation, he considered that some great subterranean river was rushing through the rock close by. But that was not possible. The sound had not been there a moment before. There had to be another explanation.
Some seed of a notion germinated at the back of his mind, suggesting that this could be a living creature. He gawped inwardly at the possibility. It seemed impossible, but what other explanation could there be?
Petrified, he waited for the sound to pass. It did not. No creature could be so big that it took minutes to pass by.
To remain was insanity. Tristan jumped into the lake and splashed back through the tunnel, the lantern bobbing at his side. He ran along the stream bed and scrambled up the cavern wall, losing his footing several times in his haste, and taking enormous risks as he scrabbled between the stalactites. He hauled himself up into the passageway, immensely relieved to see daylight.
The sound was fading.
Tristan disregarded the zomo thorns that hooked onto his nanosuit and his flesh: they would mend themselves. He hastened towards the airhopper.