Adam was once again shuffling through the streets of his hometown, which were deserted at this hour. He was about to turn seventeen and had long felt that something in his world was waiting to be discovered. He just didn't know what. That evening he was joined by his younger sister, fourteen-year-old Lena, who was far more adventurous than he would like to admit. She carried a backpack filled with torches and a compass. Natalia laughed quietly, slipping on the wet pavement. They passed old tenements whose facades seemed to pulsate in the lamplight - as if an undercurrent of life vibrated behind the closed windows. Lena noticed it first: under one of the street lamps, the shadow was unnaturally dense, as if it were absorbing the light. Something drew them to this place, even though logically they should have gone home by now. They stopped and Adam rubbed his eyes, confused: the darkness just outside the lighthouse resembled a fluid, rippling curtain. Lena didn't wait long - she reached out and touched the 'wall' of shadow. Her hand disappeared, as if she had stepped into thick smoke. Adam grabbed her wrist, but didn't manage to stop her. Before he knew it, they were both pulled through the wall of darkness. They fell softly, as if they had landed on thick grass. However, what they saw around them was unlike any place they knew. The streets stretched on endlessly under a lunar sky, and the light of the lanterns was a delicate shade of blue. The city that emerged before them was built of materials that glittered like glass and steel, though no building was like another. Shadows of beings that appeared to be mere outlines flitted along the streets. Everything was unreal, but at the same time it was tempting to come closer. Adam tried to recognise any familiar place - unsuccessfully. Lena squeezed his hand tighter, and her eyes lit up with excitement. Someone was watching them closely from one of the alleys. They heard a quiet rustling. Then a short laugh, as if a sound made by someone young. Lena moved slowly forward, and Adam had no choice but to accompany her. As they approached the corner of the street, a figure slid out from behind the glassy door of one of the tenements - tall, disconcertingly thin, with eyes shining silvery in the semi-darkness. She held out her hand, indicating to them without a word the entrance to the interior. Adam hesitated. Lena was already moving towards the unknown figure when suddenly a strange, intermittent sound came from behind them - as if someone was arranging fragments of a melody from completely unfamiliar notes. The space around them began to ripple slightly, and the shadows by the lanterns lengthened, moving towards them. For a moment, the world became incredibly sharpened and muted, like just before a storm. Adam had to make a decision: follow the mysterious figure or turn back, although he could not see his way back. Another laugh sounded - completely close by. At that moment, something was about to happen that would change their view of the border of worlds once and for all.