The night was exceptionally quiet, with the wind barely brushing the treetops surrounding Ola's house. The girl had always liked to spend evenings with her friends - Julk, Zuza and Dawid - especially when her parents went away to visit her grandparents. That evening, they felt that nothing out of the ordinary was happening until Zuza found an old cast-iron key under her pillow in the attic. - Maybe it fits the rusty padlock in the cellar? - David asked, hiding his hands nervously in the pockets of his sweatshirt. Ola furrowed her brow. The basement had always been a mystery. When they were younger, their parents had forbidden them to go in there - supposedly for safety reasons. Now, however, standing together at the entrance, they felt only a thrill of excitement and a slight fear. They walked slowly down the narrow wooden staircase. All they could hear was the creaking of the planks under their feet and quiet whispers. Julek, as usual the bravest, was the first to approach the heavy doors. It resembled the door to an old vault: covered in rust, with a round lock in the middle. - 'Try it,' Ola urged him, glancing uncertainly over his shoulder. The key entered the lock with resistance. After a moment's silence, a surprisingly loud clatter announced that the mechanism had let go. They slowly opened the door, and a chill blew from inside. Downstairs, darkness spread, interrupted only by the faint glow of the torch on Ola's phone. There was a strange smell of dampness and something that resembled old books in the cellar. Scattered, unreadable papers and rusty tools lay on the ground. On the opposite side of the wall was another pair of doors - this time with a tiny round window at eye level. - Do you see that light? - whispered Zuza, pointing to a narrow beam squeezing through the glass. Everyone froze as they heard a quiet tapping, as if someone was gently tapping the glass on the other side. Whatever was in the enchanted cellar was just making itself known. Should they open another door? Or go back upstairs and pretend nothing had happened? That evening they had to decide... But what was waiting behind the mysterious window, none of them expected.