The first chestnut leaves swirled in the wind as Lena, Bartek and their younger sister Zosia rode their bicycles through the vast clearing located at the end of Flower Lane. Shadows glided behind them and the top of the forest painted a dark green streak on the horizon. In the distance rose the silhouette of an old brick mill - abandoned for years, with a crooked turbine and an overgrown courtyard. Lena was the bravest of the three. She was the one who came up with the idea of doing something special on the last Friday of the summer holidays - a night hike under the old mill. Bartek, a year older, pretended not to be afraid, although he felt a slight prick of anxiety inside. Zosia attached a torch pendant to her backpack and never parted with her beloved plush bat. It was approaching nine o'clock when they arrived at the site. Purple clouds were gathering over the mill and the wind was swishing through the cracks in the walls. Lena spread out a blanket, Bartek took out a thermos of tea, and Zosia stared wide-eyed at the old windows, one of which was shattered. - Did you know that this mill used to run 24 hours a day? - asked Bartek, sitting down comfortably. - Dad said that at night they used to grind grain here for the whole village. - They don't grind anything here now - whispered Zosia. - But why did someone leave the lights on inside? Lena looked at the place her sister was showing. High up, on the top floor of the mill, something shimmered with a yellowish glow, as if someone had passed with a lantern just outside the glass. For a moment everyone was silent. - 'Maybe it's just a reflection of the moon,' muttered Bartek, trying not to betray himself with a trembling voice. - 'But... after all, the moon hasn't risen yet. Zosia squeezed the plush bat. - Let's go there, let's see! - suggested Lena with a glint in her eye. They took their torches, left their bikes behind and slowly, almost on tiptoe, set off towards the huge wooden doors of the mill. The boards creaked under their feet, and the wind seemed to whisper something among the bags left behind and the overturned barrels. As they stood at the very entrance, they felt an unsettling chill. There was a quiet murmur coming from inside that did not resemble any familiar sound. Lena was the first to put her hand on the door handle. - Is it already? - asked Bartek in a whisper. Lena nodded and pressed slowly. The door groaned protractedly and a dark space opened up in front of them, saturated with dust and the smell of damp wood. Suddenly, deep in the mill, something flashed again... this time it moved visibly. And then...