Lena was fourteen years old and lived opposite the old water tower. For a week, the tower had been buzzing at night, as if a sunken train was circling inside. That evening she brought home a notebook from her aunt, known for her strange expeditions. On the cover was a spiral sign and a note: Beware of city overlays. Inside she found a map of the estate with places marked in silver pencil. One place flashed in her mind, as if a blinking neon sign had gone out. Her aunt had disappeared in April, leaving only this notebook and a sketch of an unfinished street. It was the cartography section in the library, closed for months due to renovations. Lena convinced Maks, the upstairs neighbour, that he had to see it. They went at dusk, when the rangers always made a longer round around the park. The library door smelled of dust, paint and something resembling wet electricity. They turned off their torches as they passed the doorman's window, and hid between the bookcases. There was a humming noise in the silence, as if the library was breathing empty floors. Behind the service ladder was a C13 metal cupboard like the one in the notes. Lena slipped a spiral key she found in an envelope marked: Do not turn. Maks hissed: 'You really think that's a good idea at this hour.' She replied in a whisper that it wasn't the time, but the question. What will cease to exist if they back off now and stop looking? The wardrobe trembled, and a cool blue peeked through the air vent. On the door someone had penciled the name: Second Bank, and an arrow to the side. A panel in the back wall stepped back, revealing a staircase that headed up and down at the same time. On the other side hung the tracks, on which a tram without cars quietly ran. Clocks dangled from the ceiling, all set for thirteen minutes past eight. On the lowest step lay my aunt's red shawl, still warm from someone's hand. A shadow slipped out of the gloom, and then a voice sounded, very close by. "Lena, don't look back," - said someone, and the light in the library went out.