Seventeen-year-old Lena notices a strange key in her apartment block and the building seems to answer back. When she reaches for the door, something behind her moves.
Lena had always felt that her life was happening one wall away from where she stood. Her city was all concrete, wet pavements, and lit windows seen from a distance, and her block of flats rose from it like a sealed box, each floor hiding its own private noise, its own version of the truth.
That night, the third-floor landing was dark.
She came in late from her lesson, shoulders cold from the walk home, the stairwell smelling faintly of damp plaster and old cooking. The handrail still gave its familiar creak on the fourth step. The coffee stain on the wall by the second landing was still there, brown and unmistakable. Everything was exactly where it should have been, which was why the thing waiting on the wall stopped her cold.
A key hung from a nail beside the lift shaft.
It was small, iron-dark, and speckled with rust, as if it had been left there for years. Nothing about it should have seemed important. Yet its shadow stretched wrong across the wall, longer than the key itself, sharp at the edges, almost alive in the weak yellow light.
Lena stared at it, then at the note pinned beside it in uneven handwriting: Sometimes all you need is to open the door.
Her fingers closed around the key before she had fully decided to take it. The metal was colder than it should have been, cold enough to sting. Somewhere below her, in the entrance hall, came a soft rustle, then the clear click of a footstep on the tile.
Her throat tightened.
The front door downstairs was locked. It had been locked when she came up.
Lena looked toward the corridor at the end of the landing, where the last flat stood in silence, its door shut as always, as if it were waiting for someone who never arrived. The air felt different there, charged and thin, like the moment before a storm breaks. She could hear her own breathing, the quick shallow sound of it, and then another step sounded behind her on the stairs.
Slowly, Lena turned.