On the surface of the silvery Moon, among craters deeply etched into the age-old dust, the lights of the Luna-17 research station shone brightly. Inside, where fans buzzed constantly and screens pulsed, Sara struggled to contain her drowsiness. She had just read a report about a predicted micrometeorite storm. Emil, the tallest of the three scientists, was sitting by the panoramic window with a cup of synthetic coffee, looking at the Earth, which hung above the horizon like a blue jewel. Viktor, meanwhile, was studying data from the latest probe sent towards Pluto. The atmosphere that night was extremely tense; a premonition of something unusual hung in the air. Suddenly, the communications console glowed red. A sound came from the speaker, resembling a rhythmic pulsing. Sara immediately put down the tablet and walked over to the panel, Emil shook himself out of his reverie and Viktor quickly registered the readings. For a moment, they were all silent, listening to the unseen signal. It lasted less than two minutes and then went silent, as if it had never existed. It was the first time Sara had ever seen such a pattern on a monitor. It was too orderly to be considered random space noise and its source was not from any known device, satellite or probe. The system indicated that the signal was coming from outside the solar system. - This is no joke, is it? - Emil asked quietly, glancing at Sarah's screen. Before they could exchange conjectures, an intriguing image appeared on the external monitor: a light emerged from one of the darker sides of the Tycho crater, pulsating in a rhythm similar to the received signal. It was too bright and regular to be considered a natural phenomenon. - 'We need to check it out,' Sara said, feeling her heart beating faster than usual. The three explorers prepared to go to the moon's surface in a flash. As they stepped out through the airlock, their suits reflected the cool light of the Earth, and all around them stretched only silence and boundless dust. Every step raised a silvery cloud. Viktor carried a portable wave analyser while Emil tracked the direction of the pulsating light. The closer they got to Tycho Crater, the more intense the sound reverberated through their helmets - the pulse became almost tangible, vibrating in their chests. They reached the edge of the crater. They stopped, fascinated and frightened at the same time. At the bottom of the crater, among the scattered boulders, pulsed something they did not recognise as the work of man or nature. The shiny, translucent structure changed shape with each flash. Tiny luminous fragments floated around it, swirling like a dance of countless particles. Sara trembled as Viktor switched on the analyser. The results began to scroll across the screen at a speed they had never seen before. The signal turned out to be ... a code of sorts, but completely unlike any Earth language. Emil was already about to descend towards the object when suddenly a pulsating light expanded, flooding the entire space around the researchers. Their microphones registered new, unfamiliar sounds, and the monitors began to go crazy from the influx of information. At that very moment...