The school at the end of the forest was never ordinary. At least that's what those who had the courage to venture into its forgotten corridors claimed. For Natalia, Jakub and Maja, for two years it was just a building visible from behind the bus windows - a shabby silhouette against the autumn trees that did not seem to fit in with the modern edifices of the city centre. One gloomy October day, when incessant rain fell from the sky, due to the renovation of their own school, the entire 2C class was moved there. For the first few days, everyone joked about the cracking floors, creaking doors and the muffled light that shone through the dirty windows. But after lessons, when the last teachers were closing their classrooms and turning off the lights in the corridors, the building seemed to extend invisible arms towards them. Natalia, as class president, often stayed after lessons. The other day, she was asked by the class teacher to find a map of the building in a locker in the basement. She grabbed Jakub and Maja - after all, it's better together. The scholastic task quickly turned into something much weirder. Descending the narrow staircase, they entered the basement, where the air was cool and the musty smell was biting. In the semi-darkness they found an old filing cabinet. Digging through piles of yellowed papers, their attention was caught by notes that dated back to the 1930s. As Natalia pulled out one of the notebooks, they felt a slight gust of air - and then something clattered behind the wall. They stopped motionless, listening. Maja pushed back a stack of folders, revealing a brick wall with a small, barely visible flap. It was locked with an old, rusty lock, but it looked like no one had opened it for a long time. Jacob knelt by the flap and after a moment of fiddling with his keys found one that fitted. Behind the hatch was a passage, leading into a dark corridor. From a distance, they heard a strange sound - something between a child's laughter and the echo of a thunderstorm. With a slight hesitation, they looked after each other. What was on the other side could turn everything they knew about the school upside down. Natalia carefully turned on the torch on her phone and took the first step into the unknown. At the same moment, the basement door closed with a bang and its light began to flicker....