The old house at the end of the street had always made Lena uneasy. Its gloomy windows looked out at passers-by as if they hid secrets that no one should know. On this June night, however, curiosity triumphed over reason. She and Oskar, her twin brother, slipped out the window of their room, leaving their ordinary lives behind. In their hands they held a dusty key that Lena had found while tidying up her grandmother's library. She had a strange feeling that it belonged to this house. Stepping through the tall grass, they whispered slowly, as if each sound could awaken long-dormant magic. The door opened with a groan, letting them inside. The inside was different to what they had expected - the air saturated with dust, but the floors gleaming, as if someone had cared for the place. Oskar was the first to notice the clock standing in the corner. It was huge, decorated with bizarre symbols and had no hands. Strange swirling lights shone on its dial. Lena touched one of the letters and suddenly felt a weight, as if time was swirling around her. The clock rang out in a deafening voice: "One key, one passage. Ready?" Before she could retract her hand, the room shattered into fragments of light. The sky turned green and the floor pulsed with rainbow circles. They were already on the other side. In front of them, a city made of crystals was rising up, and swirling islands floated in the air. However, standing right next to them was a figure in a cloak, whose face they could not discern. The figure spoke up in a hissing voice: "We have been waiting for you. You have to make a decision - do you go back, or do you continue on?" Lena looked into Oskar's eyes. They weren't sure what to answer when suddenly....