In the small town by the river, time passed lazily until one morning posters appeared in the main square announcing the arrival of the Circus of the Night. The multicoloured letters promised shows of fiery lions, trapeze acrobats and illusionists whose secrets were known only to the stars. Naturally, the whole school was buzzing with talk of the circus, and Lena, Ada and Philip immediately decided that they had to be there in the front row. On Saturday, just after dusk, they set off together across the fragrant grassy meadow, where colourful balloons floated above the circus set up. The tent was huge and the sounds of music and joyful shouts came from inside. When they stepped inside, they felt like they were in another world: sparkling lights, a clown on stilts walking past them, a flock of white pigeons circling under the dome. The show started with a bang. First, acrobats in cobalt-coloured costumes rushed into the arena, twirling on ropes and swings. Moments later, a magician appeared, turning balls into gold coins at the blink of an eye. But what fascinated the children most was the lion show led by the mysterious Trainer, Mr Lucien, whose black cylinder and long coat were awe-inspiring. A lion named Bartek was the biggest star. He was able not only to leap through rings of fire, but also to poke and tickle the children, eliciting peals of laughter from the audience. Lena noticed that in the evenings the Trainer would talk to Bartek for a long time, as if the lion was his best friend. After the show, the children did not want to go home just yet. Instead, they snuck backstage, hoping to get Treser's autograph. They walked through strings of twinkling lights and huge crates of props. At one point they heard strange footsteps coming from the end of the tent corridor. Philip got out first and looked behind the curtain. Lena and Ada joined him and saw the empty space where Bartek's enclosure should have been. There was no sign of the lion. Suddenly there was a muffled sound, as if someone was quickly hiding something heavy. The children looked after each other with wide-open eyes. Someone was walking in the darkness behind the arena and whispering something, and the lights in that part of the tent began to flicker. Had the lion escaped? Or had someone taken it? Before they had time to come out of hiding, a shadowy silhouette moved right past them and stopped for a moment, as if it had sensed them....