Science Fiction Dilogy

From the depths of the universe Earth hears the radio signals of intelligent beings from a planet of the star system Shedar in the Cassiopeia constellation. A project is set up, proposed by the young inventor Vitya Sereda, to send a spaceship to reach the planet - but the flight will last for decades, so the crew of the spaceship "Dawn" is to be recruited from teenage students.

"Down" starship realised 27-year-long flight and appears at the Shedar system after less than 1 year of local time travel. Remote sensing verifies that one of the planets is very much Earth-like. They land on the new planet and once meet human-like creatures there that escort them to the underground city. They become unreachable for radio communications from the Earth.