The night was uncharacteristically warm for the beginning of September, and the streets of the town were full of whispers before the start of the new school year. Zosia, Igor and Lena, inseparable for years, met in the old square by the abandoned cement factory. Their conversation revolved around legends, repeated for generations, of underground tunnels that would stretch beneath the entire town. Sceptical but intrigued, they decided to see how much truth there was in it. Igor pulled a torch from his backpack. Lena, holding a notepad, was already putting together an exploration plan. Zosia was nervously playing with a silver owl-shaped key ring. "If anything happens to us, Dad will kill me..." - she whispered, but curiosity overcame fear. Behind the main building of the cement factory, they found a rusty steel hatch barely sticking out from under the ground. When Lena pushed it open with difficulty, they smelled damp and dust. Zosia shone her phone - the stairs led into darkness. They descended carefully, feeling their heartbeats increase with each step. The tunnel was cold, the sounds muffled by the thick walls. Igor stopped at a rusty sign. "Do not go any further in." - he read aloud. Lena took the picture, in a bold voice she joked: "Well, we'll definitely go further! Whoever backs out is a coward!" The tunnel branched off at a right angle. To the right, the torchlight reflected off something metal. Zosia came closer - it was an old box. As Igor tried to open it, they heard a clatter behind them. Someone, or something, was moving in the darkness.... They grabbed each other's hands. Hearts pounded and breaths turned into short, broken gasps. Igor raised the torch higher. In the semi-darkness they spotted a shadow passing just inside the tunnel wall. There was silence for a moment, and then a quiet whisper and... the light of another torch came to them from behind the tunnel break. Had someone overtaken them here? Who is the mysterious stranger? Or was it just their imagination playing tricks? The three friends stood in the darkness, ready for anything that could happen....