Marysia has always enjoyed going to the forest. Especially to her favourite corner, where a huge, spreading oak tree grew. The tree was so old that it probably still remembered knights and ancient legends. On warm afternoons, she would sit on its thick roots and read books or draw what she saw around her. On this day, she felt something was about to happen. The birdsong sounded different somehow, and the light of the setting sun made unusual patterns on the moss. Sitting under an oak tree, she noticed a small, flat stone with strange markings on the ground. The stone shone softly, although there were no flashing things nearby. - Maybe it's a fragment of some old clock? - wondered Marysia, examining the find from all sides. It was cool and smooth, but when she touched the inside, she felt a slight tingling in her fingers. At the same moment, the oak tree rustled its branches, although no wind was blowing. Mary jumped up and looked around, but there was no one around. Suddenly she heard a quiet voice: - It's good that you found me... - rang out in a whisper right next to her ear. The girl froze. It was not the voice of any bird or squirrel. The smell of freshly baked bread and red apples spread around, although she carried no snack in her rucksack. Mary raised her eyes and saw a bright ray of light that seemed to guide her around the tree. With each step she felt lighter and lighter, as if the ground beneath her feet was becoming as soft as a cushion. And then, just under the thickest root of the oak tree, she noticed something else. A small golden key was stuck in the ground. Before she had time to touch it, she felt the ground begin to vibrate gently, and more and more distinct coloured lights appeared around her. Something unusual was about to happen....