It all started on the last Friday of September, when a series of storms swept over the city. The school corridors were in that peculiar twilight, and the air was damp and sticky after the night's rain. Veronica, as usual, arrived a little too early and circulated around the almost empty school, waiting for the corridors to fill up with familiar faces. For the past few weeks, something had been changing within the school's walls, although no one had spoken out loud about it. The lamps on the second floor occasionally flickered, and some of the doors to the classrooms collected an odd amount of dust, as if no one had opened them for years - even though everyone knew they should be in daily use. On this day Veronica, led by impulse, went up to the third floor, where she rarely looked. The swinging door to the old art room caught her eye. For a moment, she hesitated to enter - after all, it had not been used for a long time after the teacher, Mrs Marczewska, retired. Suddenly Krzyś, her best friend, appeared next to her. - What is there? - He asked in a whisper, looking at Veronika with a spark of excitement in his eyes. Before she had time to answer, they were joined by Igor, coming out of a neighbouring classroom. The three of them, not hiding their curiosity, crossed the threshold of the room. Inside, a different world prevailed. The tall windows were completely covered in dust, and the floor creaked with every step. The wall opposite the door was plastered, but right next to the paint bookcase stood... a door, completely incongruous with the rest. They were made of dark wood, smooth and polished so that you could see the reflections of the children's faces. - Had someone installed them recently? - Igor asked, touching the cool handle. Veronica felt a shiver run down the back of her neck. At school everyone knew where which rooms were, and this door was not on any map. After a short deliberation, they decided to open it. Behind the door, however, there was not another room or a storage room. There stretched a narrow, spiral corridor whose brightness pulsed with every heartbeat. The paint on the walls was painted with fractals and patterns that changed with every blink of an eye. Before anyone had time to say anything, a quiet slamming sounded behind them - the door slammed shut with a bang. The three friends were now standing in an unfamiliar passage, a light flickering in front of them and making sounds reminiscent of the voices of the children in the classroom. It became clearer with each passing moment. They had no idea if or how they could get out of here, and who or what the figure that was emerging from the pulsating glow at the end of the corridor would turn out to be....