Lena, Michal and Paulina had long loved discovering new places. The forest surrounding their village seemed familiar to them through and through, but this day was different. The August sun was lazily squeezing through the dense foliage and the air smelled of damp earth. Lena was walking first, compass in hand and phone ready to record anything of interest. - 'We've really moved away today,' Michal remarked, glancing at the map on his smartphone. - 'If we go further north, we'll hit the old clearing my grandfather told me about. - That's where those treasure hunters supposedly disappeared, remember? - Pauline quickened her pace, curiosity winning out over anxiety. At one point, Lena tripped over a piece of metal sticking out of the ground. She crouched down and began to scrape away the layer of moss. After a moment, a round disc, covered with strange markings, appeared to their eyes. Its surface gently pulsed with a blue glow that seemed to come from within itself. - This... I don't think it's an ordinary manhole cover,' whispered Michael. Pauline reached out and touched the disk. At the same moment they felt the ground beneath them tremble slightly. The disk slowly opened, revealing a spiral staircase leading downwards, flooded with blue light. Without a word, Lena activated the camera on her phone. Before they had time to think, she descended first into the depths of the passage. The stairs led them lower and lower, the air temperature dropping with every step. When they reached the bottom, they found themselves in a huge hall covered with enigmatic frescoes. In the middle of the chamber a light was beaming so intense that they had to shield their eyes. When they looked around, they saw that there were tall, crystalline columns sprouting up around the hall, sparkling with all the colours of the rainbow. Suddenly they heard a metallic sound - something was approaching behind them. Lena tried to turn around to see what it was, but the light flashed even stronger, blinding them for a moment. Michael felt the ground beneath his feet begin to tremble harder and the air fill with an unfamiliar smell. There was a rustling sound behind them, and shadows began to dance across the walls. All three held their breath, feeling that they had just crossed over into something completely new. They heard a quiet whisper that did not resemble a human voice....