It was autumn. The old walls of the high school turned into a maze of riddles every day - at least that's what Andrzej, who knew every nook and cranny here, claimed. On a Thursday afternoon, the four friends, Lena, Andrzej, Igor and Sara, hid in an abandoned part of the school, where apparently no one went anymore since a teacher fell asleep at the end of a strangely dark corridor a few years ago. - 'Let's check the place out,' Lena suggested, clasping her hands nervously on her backpack. - 'Since nobody goes there, there's probably something hidden. - Maybe ghosts? - Igor tried to joke, but his voice trembled. - 'Or something much worse,' Andrew added, correcting his glasses. However, he quickly showed an arched fragment of a key he had once found in an old library. They shuffled quietly through the wide staircase and the long, creaky plank-lined corridor. The light coming through the windows painted ripples on the dusty walls. Beyond the last door - at the end of the corridor - twilight reigned. The door was massive, with a large cast-iron handle, and someone had drawn a bizarre symbol on the wood in chalk. Sara cautiously put her hand on the handle, but Andrew stopped her with a gesture and slipped the key into the lock. He turned it. The lock groaned and Lena felt her heart go up to her throat. - Ready? - Igor whispered. The door opened with a groan. Behind them stretched an unnaturally dark space. It was quiet, so quiet that one could hear one's own thoughts. Suddenly, there was a whisper somewhere in the depths - barely audible, as if someone was saying something right next to their ears, although no one was visible. Everyone froze. Lena felt all the emotions - fear, curiosity, anxiety - swirl inside her at once. She wanted to step back, but her legs wouldn't move. Then a shadow emerged from the darkness. It was tall, blurred and moved silently. In his presence, the air became thick and the walls seemed to move closer. - Who are you? - a voice rang out, deep and strangely familiar. The friends looked at each other in panic, not knowing whether to run away or stay, and then....