Yulek and Tosia were eagerly awaiting the start of the Big Show under the colourful dome of the Magic Circus. The whole town was talking about amazing tricks, magical animals and the mysterious magician Leon, who had come here for the first time. They sat in the front row, right next to the fragrant candyfloss and freshly roasted popcorn. The lights began to flicker and colourful clowns ran into the arena, spinning plates and juggling balls. Tosia clapped her hands as the dog in circus clothes jumped through hoops, and Julek whistled the loudest during the unusual tiger number. Suddenly, as the lights went out in the circus, a whisper went through the whole tent. It was the magician Leon about to enter. As his mysterious old carriage drove into the arena, something caught Julk's attention - a strange silver key was sticking out of the back of the carriage. It didn't fit in with the rest of the circus decorations; it glittered in the spotlight, as if it caught the eye of only the most daring spectators. After the show, during the break, Julek and Tosia couldn't stop thinking about the key. When no one was looking, they sneaked under the arena, backstage, where the magician's carriage stood. The silence was tense and the air smelled of mystery. - Can you see him? - whispered Tosia, pointing to the key. - 'Yes, but see, the door is slightly ajar...' - replied Julek, his heart beating harder. Suddenly, there was a quiet metallic rasp from behind the door and something began to move inside the carriage. Then...