The eternal night on the outer ring of the Day and Night Station was even darker than usual. On one side, through the panoramic windows, millions of stars stretched out, so close that it seemed as if all you had to do was reach out your hand. On the other - another change was coming. Alex, just turned seventeen and in his third month of apprenticeship on the station, could not tear himself away from the communications console. The technical light of the screens reflected in his contact lenses, and thoughts of returning to Earth swirled in his head. Almost the entire crew consisted of student-trainees from different corners of the solar system. Seventeen-year-old Elara, a Martian by birth, drummed her fingers against the table top, impatiently looking out of the window at the shadow of Jupiter. There was also Julian - the eldest of the group - who was quietly listening to a music player simulating the sounds of the forest in order to forget, if only for a moment, the cold steel floor underfoot. They had all come here for adventure, but the daily routine was becoming monotonous. The night's silence was broken by the crackle of a loudspeaker. - Again those strange impulses? - Elara asked, straightening up abruptly. Alex nodded, running his finger over the screen. Short, repetitive series were appearing on the graph. For several days, an unknown signal had been coming into the station from deep space, beyond the limits of known sectors. The commander had turned the matter over to them for observation, explaining that sometimes it was just a drifting, broken probe. But Alex had a feeling that this time it was different. - 'Have you deciphered anything yet? - Julian moved closer and leaned over Alex's shoulder. - 'The signal is unique. Each sequence looks different, as if something.... was trying to send a message but couldn't speak our language. They decided to take over the main communications room that night. It seemed that the station was asleep, but behind the walls slumbered powerful engines ready to manoeuvre at any moment. Reviewing the latest data, Alex noticed something else: the signal didn't just repeat itself; it began to change frequency at the exact moments they passed the console. - 'This can't be a coincidence,' said Elara. - 'He's reacting to us. The silence in the room grew thicker. All three looked at each other. At the same moment, the lights on the control panels flickered and a deafening sound came from outside, as if something huge had snagged on the station's hull. Before they had time to react, the automated systems closed the bulkheads, cutting off the outer ring from the rest of the station. Red emergency lights came on everywhere. A distorted, unrecognisable voice sounded through the speakers. Screens began to display alien characters that no one had ever seen before. - 'It's a signal. It's already here,' Alex whispered. At that moment, a shadow appeared in the main window, obscuring the starry sky. All three of them froze as they watched something they could not identify approach the station....