The rain was drumming against the windows of the old townhouse when Euphemia returned home from classes. She was seventeen years old and had always felt that her life played out only on the fringes of real events. While others met in the city in the evenings, she would sneak quietly into her grandfather's antique shop or, absorbed in a book, flit between the worlds of literature and reality. That night, by chance, she stumbled upon something unusual. In an unpopulated corridor in the attic, where even the lamplight seemed uncertain, she found a mirror. It was tall, standing on intricately carved legs, and its surface seemed to absorb the light. Gazing into the depths of the glass, Euphemia noticed that her reflection was slightly shifted. The hand in the mirror was moving with a delay, and in the background, the shadows of strange buildings, which, after all, were not in her house, could be seen. Her heart beat faster. She reached out to touch the surface of the glass - it was cool, but an indescribable force drew her closer. For a split second, she had the feeling that she saw someone else there. A girl her age, but from another time. Behind Euphemia, the corridor door closed and the light dimmed. Instinctively she took a step forward and.... Darkness fell. She woke up in a place that looked like her city, but everything here was different: the buildings seemed to be made of glittering crystals, the trees had silver leaves, and the sky went from sapphire to deep purple. There was someone walking down the street - the same girl she had seen in the mirror. She had short platinum hair and eyes shining like mercury. She stopped and looked straight at Euphemia. - 'You're late,' she said in a mysterious voice. - He is already here. Before Euphemia could ask who she meant, where he was, and how to get home, a low, echoing whisper sounded around the corner. The roots of the trees began to move, and luminous figures - neither people nor shadows - appeared around her. The mysterious girl cast Euphemia a warning glance and pointed to an old doorway leading to the city's underworld. Euphemia felt her heart pounding and hundreds of questions boiling in her head. She already knew that this was no ordinary adventure and that the mirror was just a gateway. Should she trust a stranger? What hides in the underworld, and who is the mysterious "He"? The creaking door opened slowly, letting in an ominous light. Euphemia took the first step down the stairs....