In the far north, where the sun never sets completely, lay a city built entirely of glass. When viewed from afar, the glow of the crystal towers mingled with the mist and it seemed as if the city flowed over the lakes that surrounded it. Cartographers of old had avoided the place on maps, describing it as too dangerous to visit, but for Lara, Kasper and Mira it was an everyday occurrence. Lara, the bravest of the three, had always felt that there was something more hidden beneath the clear streets and cool surface of the city. For several months, she had been awakened nightly by shadows moving across the glass ceiling of her room. Fascinated by ancient magic and forgotten stories, Miira meticulously kept a notebook full of legends about the Glass Man, who appears to warn the inhabitants of disaster. Kasper appreciated the logic the most - when the girls told of their premonitions, he shrugged his shoulders, but anxiety kept him awake too. On a summer evening, when the wind brought an unusually milky mist from the lakes, Lara found a small glass key under her window. It was as cold as ice, and its surface seemed to vibrate under her fingers. Kasper, although sceptical, could not explain why the sky was reflected on the key, even though it was evening. Miira immediately recognised the mark engraved on the key - the same symbol appeared on old maps of the legendary 'Lower Dwellings', closed for a hundred years. Under the cover of darkness, keeping close to each other, the three friends set off down the glass staircase leading to the city's oldest underworld. The deeper they descended, the thicker the fog became, and a chill appeared on their skin, as if something invisible was moving the air. The door to which the key fitted was almost invisible - it looked like a section of wall, but Lara felt the key suddenly become hot. As she turned it in the lock, a quiet metallic sound pierced the air, and a figure woven from shadow and light emerged from within, faceless but with eyes glowing with a familiar radiance. At the same instant, the sound of glass shattering rang out above them, and the floor began to tremble slightly. For a moment, everything fell silent, and then a whisper sounded from the depths of the corridor: "You were the ones who were supposed to wake up the city.... But are you ready to know the truth?"