Lena was fourteen and building a radio from reclaimed components. On the roof of a block of flats in Gdynia, the wind wheezed between the aerials like a question. Her best friend Niko held the coil and the phone glowed with a graph. The physics assignment was to catch anything from space and prove the source. Lena aimed for the zone of silence over the Baltic, where the satellites were stubbornly silent. She rearranged the filters like a DJ until the dials were hot with nerves. Suddenly the chart wavered and a rhythmic, unearthly click sounded in the headphones. Niko blinked, adjusting the sensitivity, and counted the intervals like a stubborn metronome. The clicks arranged themselves into a code they had once seen on a ham radio forum. Morse code, but strangely abbreviated, as if the sender had ended each letter in a whisper. Lena began to decode, and words slowly emerged from under the noise. Her name, the coordinates of the school and an old cipher described in the school's astronomy textbook. Beneath the signal, an even deeper tone echoed, like the echo of a hidden engine. The coordinates pointed to the basement of their school, right under the robotics lab, at night. This made no sense, so of course they went there the next evening. The corridors smelled of dust and salt, and the emergency light blinked green. Behind the warehouse, a gymnastics mattress dangled from a hook next to an old electrical box. Lena touched the casing, feeling a slight tremor as if a river was flowing inside. Niko put his ear to it and heard the same bass from the recording. On the box was a sticker with the logo of the Amber programme and the number three. Under her fingernail, Lena felt a crack that didn't match the design. She moved the panel and the metal buckled quietly and sprang aside. Behind it, a narrow tunnel with handrails was revealed, descending deeper beneath the foundations. A blue glow oozed from the darkness, pulsing according to the code from the radio. Niko took out his torch, but the phone screen recorded the new coordinates on its own. They were not places, but moments, marked by the date of their test tomorrow. Somewhere down there it clicked, like an answer to a decision they hadn't yet made. Lena grabbed the railing, looked at Nika and heard her name, this time whispered from below.