Marta, Kuba and Oliwier had long dreamt of a trip together that would forever remain their secret. Having left the bustling streets of the Mountain Town, they approached the gloomy edifice of the Hotel Pod Emerald Deer. The building, although it had stood closed for years, seemed to live a life of its own: the panes of glass in the windows reflected the last rays of the sun, and the old, ornate columns bent under the weight of time. Stories about the place circulated in the neighbourhood, but none of the adults dared to visit it after dark. Martha, however, had found a map of the underground and a floor plan of the hotel in online nooks and crannies. Now, armed with torches, they felt a slight shiver of unease, even though they had been laughing and joking just a moment ago. They were walking through the cool, empty hall when suddenly Cuba stopped at an antique lift, laced with cobwebs. - It can't be... - he whispered, as a single button on the lift panel glowed softly. - Maybe it was left by some workmen? - Martha tried to sound reasonable, but her voice was quieter than usual. Oliver glanced around the corner. - The whole floor was dark, like a well. After all, there's been no electricity here for years - he muttered. Kuba, despite his anxiety, couldn't stand it - he reached out and pressed the button. The lift hummed, the light flared more strongly, and the metal door slid open with a protracted groan. Inside it was clean, as if someone had just cleaned it. In the middle of the floor lay an object that, at first glance, appeared to be an ordinary black notebook. Marta picked it up carefully. - Do you think... we should get in? - She asked, looking uncertainly at the boys. Silence filled the space. Finally, they decided to go inside. The door closed with a clatter, and the button with the number "-2" lit up on its own, although neither of them touched it. The lift moved down faster than they had expected. At one point the light flicked on and went out completely for a moment. When it came back on, they heard a deep, dragging sound and felt a slight jolt beneath their feet. The notebook opened by itself, almost as if something had moved it. On the first page there was only a single, freshly scrawled inscription: "Whoever crosses the threshold will not forget this journey". The lift stopped braking and strange, unfamiliar lights began to flash around them in the darkness. From behind the door came a quiet whisper that they could not identify. Suddenly, the lift came to an abrupt halt and there was a clatter behind the door, as if someone or something was waiting on the other side....