The rain drummed against the windowsill as Lena gazed out of the dusty window at the mansion engulfed in fog. The tenement she had moved into with her family only a week before had already managed to awaken her anxiety and fascination. There was a lack of light, the floors creaked incessantly, and puzzling murmurs drifted through the corridors at night. That afternoon she returned early from the library. In her pocket she kept an old key she had found between the boards of the attic. Small, brass, with an intricate head. "I wonder what it fits into?" - she muttered, turning it in her hands. Soon Lena found herself on the third floor. One door at the end of the corridor stood out: it was almost invisible, as if someone had deliberately painted it the same colour as the wall. With a trembling hand, she inserted the key into the lock. To her surprise, the lock gave way without resistance. Cool air gushed from inside. Behind the door, however, was no ordinary room. A narrow corridor led to a huge, cracked mirror, standing alone in the semi-darkness. Its surface rippled as if it were made of liquid silver. Lena stepped closer and saw her reflection - but something was wrong. The girl on the other side of the mirror had an identical face, but her eyes glowed with an unfamiliar violet light. She heard quick footsteps behind her. She turned and faced a boy, perhaps a year older than her. He was pale and his gaze was piercing. - Can you see it too? - He whispered, not taking his eyes off the mirror. Suddenly, a piercing scream came from inside the glass, and the whole tenement shook in its foundations. Lena felt something invisible begin to pull her through the surface of the mirror. The boy threw himself to catch her, but their hands parted - Lena plunged into the sticky, cold goo....