2500 AD. He is a talented scientist, practically exiled on an expedition to a distant planet for speaking about an inconvenient truth. Their crew is struck down by an unknown bacteria, and is forced to send out an SOS signal in the hope that someone will respond.

А little bit of lore:

The action takes place in the distant future, when space travel has become commonplace, people have populated more than one planet and established contacts with several extraterrestrial civilizations.

People have spread throughout space, just as alien races live among people. There are planets where non-human beings predominate, and those where all races are approximately equal.

And there are three planets that humans have completely populated: Earth, Earth-2 and Earth-3.

The original planet Earth, where humans initially lived, has been practically destroyed by human greed: natural resources have been plundered, nature is suffocating from industrial waste. Earth is practically unsuitable for life, inhabited by the lowest caste of humans who were unable to migrate to other planets.

Earth-2 and Earth-3 are planets where humans migrated from the first Earth. They are populated approximately equally and have a climate similar to that of Earth. Slowly but surely, humans are worsening the ecological situation on these planets as well, and the structures that should counter this are inactive due to corruption.