Janek always thought their school was a bit strange. Maybe it was because the building was more than a hundred years old, and in the basement you could sometimes hear scrabbling, as if someone was tiptoeing around in there. One afternoon, when most of the students had already left, Janek and his friend Zosia stayed in the art room to finish their artwork for the competition. That's when something unusual happened. A strong gust of wind slammed the door and the lights went out in the corner of the room. As Zosia reached under the table for her crayons, her hand came across something strange - a loose board in the floor. Fascinated, they began to carefully uncover more boards and suddenly a dark opening appeared to their eyes, with a staircase leading downwards. - Do you think we should go down there? - asked Janek, trying to hide the tremor in his voice. - If not us, then who? - answered Zosia, lighting up the hole with the torch from her phone. The stairs were old and creaky, and there was a barely audible noise from below, as if someone was whispering behind the wall. After a few minutes of cautious descending, they found themselves in a wide stone corridor. Old paintings hung on the walls, whose figures seemed to follow their every move. At one point Janek stumbled and touched a damp brick - then the wall slowly slid open, revealing the entrance to a small chamber. Inside, in the middle of the floor, lay an old, rusty key and a mysterious notebook covered with strange symbols. Suddenly, there was the sound of footsteps somewhere deep in the corridor. Someone or something was coming towards them. Janek and Zosia looked at each other terrified....