Autumn twilight was turning the city into a network of golden lights piercing through the fog, and Lena clutched a black-framed notebook under her arm. She rushed through the now deserted streets, passing faces glued to the windows lit up by computer screens. She wasn't going to get home on time that evening - and not because she liked breaking the rules. When she reached the square by the old, ivy-covered clock tower, her three friends were already waiting there. Igor, with a rebellious look on his face and a bandage on his left wrist, smiled communicatively. Marta glanced nervously at the tower entrance, while a quiet, thoughtful Olek pulled torches and chocolate bars from his backpack. - Are you guys ready? - Lena looked at them, and her voice sounded serious, although her heart was beating faster than usual. She knew this was no ordinary trip. She had been dreaming about this place for months. Whenever she closed her eyes, she saw a circle of grey, cracked stones at the top of the tower - lights swirling like an aurora around something.... that she could not describe. They climbed slowly, quietly, through the narrow, craggy staircase. The echo of their footsteps reverberated off the walls, and with each floor the air grew heavier, saturated with stuffy dust and something indefinable - as if sensing their presence. The top of the tower proved more spacious than the outside would indicate. At the very centre waited a circle piled with stones, covered in mysterious signs. There was a sound in the air that could not be named - more palpable than audible, astringent under the skull. Igor tentatively touched the nearest boulder, twitched but did not withdraw his hand. - They look... as if someone had deliberately arranged them here,' he whispered. - These are runes - replied Lena, looking through the pages of her notebook. - I drew the same ones at night, although I had never seen them before. Marta knelt by one of the stones. - These marks... changing shape? I swear, they looked different just now! Lena felt the heat ignite in her hands. The notebook trembled. The patterns on the pages began to swirl, as if they were coming together with stones. Suddenly there was a crackling sound and the wind picked up, swirling inside the tower. Olek stepped back, but did not manage to make a sound. The stone circle grew brighter and brighter, and Lena felt something pulling her inside - the air thickened so much that she couldn't catch her breath. The friends looked at each other in horror when suddenly the ground began to tremble beneath their feet, and one of the boulders lit up with a blue glow.... At the same moment, heavy footsteps sounded on the stairs. Someone, or something, was approaching fast, and Lena was still stuck in the centre of the stone circle, unable to move, surrounded by a light that was becoming more and more intense.