Przemek stood in the attic of his grandfather's old house and looked closely at the cobwebs stretched under the roof. He liked coming here - between the boxes, old books and lots of things that had long since fallen out of use, he felt like a real explorer. This time he was accompanied by his younger sister Lena, who did not leave him an inch behind. - Do you think we will find anything interesting? - Lena looked at Przemek with big eyes. - There must be something unusual here,' Przemek replied, moving a box full of old maps and paper aeroplanes. Suddenly, the end of something that looked like a piece of old wood was sticking out from under a pile of cardboard boxes. When the children pushed the boxes away, they discovered an old, narrow ladder attached to the ceiling. - Can you see that? - whispered Lena in disbelief. Przemek grabbed a rung and gently pulled. A piece of the ceiling moved away and a dark opening appeared above their heads. At first the children were hesitant - no one had ever mentioned that there was a hidden passage in the attic! - but curiosity was stronger than fear. The ladder led high up, through a narrow tunnel, higher and higher. When Przemek and Lena climbed to the top, they saw something that took their breath away: above the house there was no longer a roof, just soft, thick clouds to tread on. Where there was normally a plain blue expanse, there stretched a whole land made of clouds - silvery bridges, bizarre castles and swirling islands of clouds. A bird the size of a small car flew over their heads, and far away, among the clouds, were the silhouettes of other creatures they had never seen before. Lena grabbed her brother's hand. Amidst the white hills of clouds, a few dozen metres away, a luminous figure in a long cloak appeared and slowly began to approach them....