The young man is looking for his father - mathematics professor Peter Hogarth, who was missing while working on a secret US government project. This project was about decoding, translating and understanding transmissions from intelligent extraterrestrials.

Professor Jerzy Jastrzębski on "Voice of the Lord":

While Solaris was the most popular among Lem's books and made the author probably the most famous, the Voice of the Lord written soon afterwards delighted connoisseurs. This is not an "action novel," but more of intellectual adventures here than western quarrels. And as it often happens with similar adventures, their experience can deeply affect the reader, change his vision of the world, view of knowledge and values.

The story of research on the mysterious neutrino signal told by Professor Hogarth is therefore a philosophical treatise rather than a plot. The questions that are asked of the cosmic message are essentially threefold: first, who are they, if any, the sender of the "letter" ?; secondly - what is the meaning of the "letter" and what are the intentions accompanying the broadcast ?; thirdly - how can Earthlings use the sent signal practically?