Helenka had always loved old books. They smelled of dust and adventure, and each page rustled like the wing of a mysterious creature. However, the greatest adventure awaited her not in any novel, but in real life. One cloudy afternoon, her mother asked her to go to the city library to get a book for her younger brother. Cuba, her brave, slightly stubborn brother, necessarily wanted to accompany her. The library was as quiet as ever, but something seemed different that day. The elderly librarian winked at them mysteriously and then disappeared between the bookcases. Helenka looked at Kuba suspiciously. - 'See, I think that door over there was locked earlier! - he whispered in a whisper so clear that it echoed back to him from the darkness. They decided to look into the old, abandoned wing. The door creaked open in a draughty manner and the cold air shrouded their faces. The shelves bowed under the pressure of thick volumes, some covered in cobwebs. At the end of the corridor, between the cupboard and the wall, Cuba spotted something strange - a large oval mirror framed in a brass frame overgrown with carved vines. Helenka stepped closer. Instead of her reflection, she saw a swirling mist in which indistinct shapes shimmered. Suddenly, the mirror began to make a quiet, melodious sound, as if calling them inside. Cuba was the first to touch the surface - his fingers penetrated the glass as if it were water. - 'Helenka, it's a portal! - ' he whispered excitedly. The girl hesitated only for a moment. On the other side of the mirror she could see a sunlit clearing and strange, colourful creatures shimmering among the trees. - Come, let's see where it leads - she whispered to her brother. Carefully, with hearts beating in a frantic rhythm, the children slipped through the portal. In an instant, they smelled damp earth and sweet flowers. They heard laughter, chirping and... was it really a group of small, talking foxes watching them from behind the ferns? Suddenly, a quiet whisper came from behind the dense bushes: - Help us... You are the chosen ones! - The foxes looked at Helenka and Kuba with hope and concern. There was the sound of heavy footsteps in the distance and the children felt that the adventure was just beginning....