The Asteroid Circus arrived in the town in the middle of a June night. In the morning, on the hitherto empty square, there was already a huge tent with dark blue and grey stripes, and coloured lights flashed all around it. Simon and Lena, three 13-year-olds with an unusually vivid imagination, were the first to notice that something was wrong - at the back of the tent someone had set up three cages, covered with sheets, and from one of them came a quiet, metallic laughter. The whole town had already been buzzing about the shows since the morning. Everyone was talking about artists from all over the world, amazing acrobats and animals so strange that they were indescribable. But that was not enough for Simon and Lena. They decided to see what could be found behind the curtain before the other visitors were seated in the audience. As the crowd poured inside the tent in the evening, Lena smuggled a torch in her pocket and Szymon hid a drawing notebook. They had planned it all: during the main show, when all the lights would focus on the arena, they would sneak backstage and discover what the cage of metallic laughter was hiding. The show's finale was to be the grandest in circus history. The lights went out. The headmistress in an owl mask came out into the arena and announced the start of a number that no one would forget. Then Lena tugged Simon by the sleeve and pointed to the spotlight-lit corridor leading to the back room. Simon's heart pounded in his chest as they squeezed past crates and ropes. In the shadows behind the arena they found the cage. The sheet had already been removed. Inside sat someone - it was hard to tell if it was a human or a mechanical puppet. The figure's eyes shone with an unnatural light and a quiet, metallic laughter came from its mouth, getting louder and louder.... Suddenly, they heard someone's footsteps, and a silhouette in a cylinder leaned out from around the corner. Simon and Lena froze, trying not to breathe too loudly as the stranger headed straight towards them....