Key under house number 13

Time passed slowly in the apartment building on Blackberry Street. Everyday life here was as orderly as the string of laundry hung by Mrs Irena in the inner courtyard. Anka lived on the third floor, in a flat that smelled of coffee and old books. One hot afternoon, as she was returning from the shop, something glinted under the doormat of house number 13. She bent down and picked up the object - a metal key, all twisted and laced with tiny letters she couldn't read. She looked at it from all sides, convinced it belonged to one of her neighbours, but none of the locked stairwells or bike lockers would accept the key. A new tenant moved into the tenement that day - Igor, a student with two huge suitcases and a camera hanging from his shoulder. Anka, shy by nature, decided to chat this time and soon explained the case of the mysterious key. Igor, intrigued, suggested they try it out together in all the nooks and crannies of the building. Together they went through cellars, attics and old cells. Doors creaked and slammed, but none matched the key's odd teeth. Finally, they entered the courtyard. Dusk had fallen, the lights from the windows cast fantastic shadows on the pavement. Suddenly, Anka noticed that something she had never seen before had appeared on the brickwork under the old lamppost - a narrow, hitherto invisible crack, as if someone had scratched the outline of a door in the brickwork. Igor looked at her communicatively, and Anka felt a thrill of excitement. Could it be that the key was meant to open a door that no one else had seen? As they approached the mysterious crevice, the light of the lantern flicked on strangely, as if for a moment reality unfolded to reveal something they should not have seen....