The storm hit the windows of the Wanda Rutkiewicz Secondary School with such force that the panes shook and the lights dimmed for a moment. It interrupted Professor Baek's lecture on black holes, which pleased most of the students gathered for the school's physics night. However, not all of them - Alicia felt that something was wrong. She was intrigued by an incessant creaking somewhere above their heads. As if someone was walking through the corridors of the top floor, which everyone knew had been locked up for years. She had gathered with a group of her friends: Michal, whose imagination went far beyond reality; Susie, who always carried a torch and old keys found in the cloakroom; and Dominic, the only one who had the courage to scour every nook and cranny of the school. - Did you hear that? - whispered Alicia as the storm began to quiet down a little. - 'There's someone out there. - Maybe just the wind,' replied Michael, although he looked less certain than usual. - 'Come on, let's check,' decided Zuza, pulling a huge old torch from her pocket. - 'Since everyone thinks this floor is haunted, we need to see it with our own eyes. They squeezed through the cloakroom and climbed the steep stairs to the third floor. The door was locked. Zuza smiled mysteriously as she took out one of the keys. With surprising ease she turned the lock and the door gave way, creaking ominously. The corridor was plunged into semi-darkness. Dust swirled in the air and old maps and posters from a decade ago hung from the ceiling. Each step seemed louder than the thunderclaps outside. There was quiet laughter in the distance, though neither of them spoke. Alice felt a chill run up the back of her neck - she wasn't sure if it was the chill or the emotion. Suddenly Dominic stopped abruptly, extending his hand in front of him. In the light of the torch they saw a shadow moving at the end of the corridor. The shape was indistinct, as if someone crouched behind a pile of old cupboards. - Did you see it? - whispered Michael, squeezing Alicia's hand. - 'We have to move on,' replied Zuza, although a note of uncertainty trembled in her voice. They slowly walked closer, and the shadow moved suddenly, disappearing behind the door to the biology room, which they knew very well no one had opened for years. Then there was a clatter, as if something heavy had fallen to the floor. Zuza raised her torch up, and the others froze in stillness. At that moment they felt someone or something watching them from the darkness. A grave silence filled the corridor, broken only by the breathing of a group of friends. They took another step forward - and then the door to the hall began to slowly open, creaking louder than anything they had heard that night....