Ola, Maks and Lena were spending a summer afternoon in the forest outside the town. It was there, among the old oak trees, that was their favourite spot - a clearing surrounded by ferns, where the sun spilled out in golden patches on the damp earth. On this day, however, something was different. Instead of the usual laughter and conversation, a strange gust of wind swept across the clearing, and the leaves on one of the oak trees moved violently, though the rest of the forest remained still. Maks came closer, attracted by the unnatural rustle. For a moment it seemed to him that the trunk of the tree was rippling as if it were made of smoke. "See here!" he called out, pointing to a small door cut into the bark that had never been here before. The door was only slightly larger than a school notebook, with strange symbols carved into the surface. Ola smiled broadly. "This must be a joke! Who would do such a thing in the middle of a forest?" Lena, usually the most cautious of the three, crouched down and touched the door with her fingers. At the same moment, the world around her swirled, as if the air had suddenly thickened. The door opened on its own, revealing a dark corridor from which a soft, bluish light was seeping. From within it came a soft, melodious whisper, unintelligible but strangely soothing. The friends looked at each other with a mixture of excitement and anxiety. Maks, who had always dreamt of adventure, moved first and slipped his head into the opening. Before him stretched a world completely different from the one they knew - the sky shimmered in shades of purple and the trees were as tall as skyscrapers and pulsed with light. On one of the branches he saw a creature resembling a miniature dragon watching him intently with amber eyes. "Come on, you have to see it!" he whispered in exultation, unable to take his eyes off the fascinating landscape. Ola and Lena hesitated for a moment, but curiosity soon won out. They walked through the door together. As soon as they stood on the other side, they heard a deafening crack behind them - the door closed with a bang and melted into the air. They were alone, in the middle of an unknown, delightful but disturbing world. The clatter of someone's footsteps could be heard in the distance, and a luminous shadow cut through the purple sky....