Cuba loved to play in his room in the attic. What he liked most was to climb on the soft armchair and look out of the window at the big, fluffy clouds streaming across the sky. One afternoon, as the rain drummed against the window, Cuba noticed something strange. Behind the wardrobe, which he had never looked at closely before, something silvery was flickering. Curious, the boy pushed the wardrobe away. To Kuba's eyes appeared a small door, quite invisible from a distance. It was painted blue and surrounded by white clouds painted as if with a fairy's brush. Sitting on the handle was his favourite plush cat Stefan, who suddenly.... purring! - Stefan, can you see it too? - whispered Kuba, trembling with emotion. The cat only meowed and jumped down to the floor. Kuba, unable to restrain himself, carefully opened the door. There was no wall behind them, but a thick, soft mist. The boy felt a slight gust and heard laughter, as if someone was playing merrily. Kuba looked at Stefan, who boldly jumped into the cloud, leaving a trail of paws behind him. Cuba took a deep breath and followed the cat. After a while, he found himself on a large, fluffy island made of clouds. All around floated other islands, some had rainbow flowers in bloom, on others trees made of candy and candyfloss grew. Cuba heard the sound of bells. A balloon ship appeared in front of him and someone waved at him with an invitation. Kuba felt his heart beat faster. Should he get on the ship? Is Stefan already there? Suddenly, from one of the cloud islands, someone called Cuba's name loudly....