The first bell in September never sounds the same, but this year it was particularly strange. Lena felt it as soon as she entered the new high school building - it wasn't even the creaking floors or the smell of tiles washed too early in the morning. As soon as she crossed the threshold, she felt as if the school had come alive and was looking at her closely. She shifted her backpack closer, feeling the gaze of the older students and trying to find room 107. Fortunately, after a while she saw a familiar face - Alex, the boy from next door whom she had known since childhood. He waved her hand and together they moved towards the classroom. - Did you know that the bell here hasn't worked for a week? - whispered Alex, shaking his head with feigned amusement. - 'The teachers call us to class themselves, as if we were little children. They walked through empty, bright corridors hung with posters of school circles and reached the maths room. Lena looked around the interior - walls hung with patterns, a huge window and an an old, stained, green journal lying alone by the blackboard. It was no ordinary notebook, but a huge, leather-bound volume. She had the feeling that someone had placed it here not by accident. The lesson passed slowly. While the others were busy with equations, Lena glanced at her diary. Every now and then the teacher - Mrs Olszewska - glanced at it nervously. Towards the end of class, Lena heard a whisper: "Keep an eye on the diary" - when the teacher left for the secretary's office for a moment. Alex nodded to Lena, as if to encourage her. She was tempted to come closer. She picked up a couple of sheets of paper as if she wanted to jot something down and moved silently to the desk. She opened the journal at random. The thick pages were filled not only with students' names and grades, but also with strange symbols, coloured charts and even entries that looked like notes from experiments. The longer she read, the more the feeling grew in her that she was looking at something she shouldn't be seeing. At that moment, the classroom door opened silently. The physics teacher, Mr Czarnecki, appeared in the threshold, sweeping the room with a fleeting glance. He kept his gaze on Lena and the journal, and silence hung in the air. No one spoke, and Lena had the feeling that what would happen next would change not only her day, but the whole school reality....