Sixteen-year-old Nela collected old radios because she liked the noise reminiscent of the breath of the sea. On a November afternoon, the signal returned, tapping with a rhythm she didn't know. The hands of her compass began to spin until they stopped at an old planetarium. The astrolabe stood over the tracks, the dome darkened, but the glass was decorated with the glitter of meteors. Jonah, her neighbour a year older, met her at the rusty gate and raised an eyebrow. He said the place had been unplugged for a long time and was a little too quiet. Nela bit her lip, picked up the aerial and walked in, smelling the dust, paraffin and cool echoes. Under the dome were faded painted constellations, and on the wall hung a calendar with the Day of the Shadowless marked. In a locker by the projector she found a map of the city, where the streets were reflected as if in a mirror. Beneath the drawing was a notation: The shadow line will meet the track line at midnight. The compass reassured, pointing to a gap in the floor, which was masked by a layer of tarnished glass. The projector, supposedly dead, began to buzz, scattering tiny dots of unseen stars above them. The stairs led down into a windowless chamber where the floor was liquid, but not wet. Reflected stars shimmered on the surface, though only concrete and rust stretched above them. The radio stopped crackling and uttered numbers she had known for weeks in a whisper. - 'Don't try,' Jonah said, glancing at her as if someone else was asking for him. - 'If this is the passage, we'll find the way before it finds us. Nela dropped the bolt, which didn't sink, but scoped out the rings as if she were writing in an unfamiliar alphabet. The compass startled and locked the needle, pointing it directly at the reflected, inverted clock below the surface. They stopped at the edge and stood carefully, and the mirror took the weight, though it trembled. On the other side hung the city, with trains gliding sideways and slow, huge clocks. In the taffrail she saw a girl resembling her, with a scar that Nela did not have. The stranger wrote a number in the burn with her finger, identical to the frequency of the last signal. The dome above their heads trembled and the luminous stars slipped away, as if something was chasing the map. - 'Time is running out,' whispered the stranger silently, arranging her lips in words they could not hear. Jonah tightened his fingers on the strap of the radio, and the gap in the mirror began to narrow. The girl in the taffy added two more marks, then looked Nela directly in the eyes. - 'Not alone,' she read from her lip movement, before the mirror trembled like a taut membrane. As Nela reached out her hand, something icy gripped her from underneath.