Nadia had always loved gazing at the stars from the roof of an old townhouse on the outskirts of the city. That evening, as the silver moon hung low over the rooftops and Alek and Lena climbed up onto the roof behind her, she had a premonition that something unusual was about to happen. - What if there really is something beyond the world we see? - Alek asked, resting his head on his knees. His voice sounded strangely serious. - Something like an alternative world? - Lena tried to laugh lightly, but her eyes were shining with curiosity. Then Nadia noticed a symbol on the brick wall of the chimney that hadn't been there before. It looked like a cross between an eye and a star. When she touched the design, one of the bricks made a deafening sound and shifted slightly. Intrigued, the three of them began to gently push the bricks away, careful not to make any noise. Suddenly, a small tunnel opened up, leading downwards.... - 'I think this is a stupid idea,' whispered Alek, but by now they were all kneeling at the entrance and staring into the darkness. They descended the slippery spiral staircase. It was getting colder and colder. At last they found themselves in a wide corridor, illuminated by a pale blue light. The walls were covered with strange paintings, depicting cities neither of them recognised. When Lena touched one of the walls, the painting shimmered and the the corridor began to change. Rainbow streaks of light spilled across the floor and a whisper pierced the air, as if someone right next to them had said their names. A soft, metallic sound came from around the corner. Nadia glanced at Alek and Lena, but they were both mesmerised by the sight of the city that slowly emerged at the end of the corridor - towers floating in the air, streets made of crystal, and shadows moving as if against the laws of nature. Then, suddenly, the light dimmed and a tall, cloaked figure emerged from the darkness and raised his hand towards them....