For hundreds of thousands of years, ships of earthlings have been plowing the expanses of space. Humanity has grown, gone beyond the solar system, came into contact with extraterrestrial civilizations, won a bloody war with ghosts - representatives of a mysterious non-humanoid race. However, the struggle is not over: from time to time ghosts again remind of their existence, then the Church of Light comes to the rescue - in everyone believes this. But who will help the priest-investigator of the Church of Light who has lost his faith? Perhaps a colleague in misfortune? Brother Gabriel doubted the dogmas of the holy monastery; Brother Isaac never believed in them, and he did not want to be an investigating priest. But what difference does it make who you are and what you believe in when you need to save the world?