The night always seemed ordinary to Kacper, even if the trees in the park by the school cast long, swaying shadows. This evening, however, something was different. Lena, his friend two years older, was sitting on a bench under a huge oak tree. Her eyes glittered in the lantern light, and in her hands she clutched an old, faded key they had found earlier at the bottom of a drawer at her grandmother's house. - 'Look, there's something shining there,' Lena whispered. Kacper furrowed his eyebrows and looked in the direction indicated by the girl. By the roots of the oak tree a tiny, pulsating glow was glowing. They struggled through the tangled branches and soft moss until they reached the source of the light. There were outlined circles in the ground, as if someone had carved a secret sign here. As Lena placed the key in the centre of the largest circle, the ground vibrated and a quiet sound resembled the distant ringing of a bell echoed through the air. For a moment, the light intensified so much that they had to squint their eyes. When they opened them, there was a gaping hole in front of them - no ordinary hole. Through it they could see a shimmering city, with a river of brilliance flowing through the streets and bizarre butterfly-like creatures with transparent wings gliding high above the rooftops. Lena was the first to approach the portal. - Do you think we should go in there? - She asked, turning to Kacper. Before he had time to answer, a whisper came from behind them: - It's not always what you discover that will allow you to return.... As the boy and girl turned abruptly, they saw a figure dressed in a cloak shining like the surface of water. The mysterious stranger was slowly approaching them. There was a smell of wet moss and sparks in the air. Lena squeezed Kacper's hand and he felt his heart beat faster. Will they get through the gate? Who is the mysterious newcomer? What awaits them on the other side? The answers hid just beyond the luminous boundary, but for now - the light of the portal flickered and the quiet voice spoke again....