The Jan Karski School always looked a little strange at night, but that evening, when the last bus had left and the lights in the corridors dimmed, the four teenagers hid under the stairs instead of going home. Wojtek, the bravest of them, argued that they had to do it - to cross the threshold of the old boarding school, a building half of whose rooms had not been used for many years. Bartek and Ola hesitated, but Magda had long since decided that she would not let go. They wandered slowly through the corridor, clutching their torches and phones tightly. Everyone had heard those legends about chamber number 13 - the room where a schoolgirl suddenly disappeared in 1978, and then the door was padlocked forever. That night, however, the padlock was hanging, but it seemed that someone had recently tried to cut it. There was a red ribbon hanging on the doorknob, which had not been there before. They walked closer. Wojtek touched the ribbon, and then they heard a quiet whisper from behind the door: "Leave it...". Ola squealed and stepped back, and Magda looked at Bartek and Wojtek with a mixture of fear and excitement. The tension grew as another whisper ran through the corridor: "Who's there? Wojtek swallowed his saliva and slid the torch under the door, but the light reflected off something that looked like someone's eyes. Magda took a step forward, but suddenly their phones began to go crazy - the screens flickered and the torches went out. In the darkness, they heard heavy footsteps from behind the door. Someone was evidently coming towards them....