Ola, Bartek and Lena always enjoyed their adventures together after school. The school was located in an old building remembering the times of their great-grandmother, so there was no shortage of creaking stairs and dusty corridors. One Friday afternoon, when most of the children had already gone home, the three friends decided to take a look in the basement. They said no one goes in there because it's scary. Ola, braver than the rest, whispered: "Let's see for ourselves if it's true!" The stairs to the cellar were dark and cold. Lena turned on the torch on her phone, which barely dispelled the thick twilight. At the very end of the corridor stood an old door painted green. They trembled with every gust of wind, even though there were no windows. Behind the door was a tiny room full of cobwebs. In the corner stood an unusual clock. It was huge, reaching almost to the ceiling, and its hands moved in reverse. The numbers on the dial looked as if they had been written by someone left-handed. Bartek carefully ran his finger over the carved numerals. The clock started ticking faster and faster. Suddenly, the torchlight began to flicker. Shapes began to emerge from the shadows on the walls. At first it seemed to be just a play of light, but then Ola noticed that one of the shadows was waving its hand at them and smiling broadly, even though it had no mouth. Lena squeezed Bartek's hand, and Ola tried turning the torch off and on again. But it didn't help-the shadows became more and more distinct every second and moved towards them, as if they wanted to tell them something or invite them to play. The moment the largest of the shadows reached out to them with a hand made of darkness, the clock made a strange, melodious sound and.... everything around them began to change. The walls stretched out, the floor began to ripple and a wide staircase leading nowhere appeared in front of the three friends. Bartek looked at Ola and Lena: - Now what? - he asked in a whisper. A world of shadows stretched before them, inviting them to cross the boundary of reality. Should they move on or go back? But was return still possible...?