On the planet Arb, very much like Earth, scientists—people who once already brought terrible evil to humankind—have become monks, and science itself is completely separated from everyday life.
Erazmas is a young monk from the community (now they are called concentrates) of the luminary Edhar, a refuge for mathematicians, philosophers, and scientists protected from temptations and wickedness of the outside, secular world—the extramuro-s—by thick monastery walls.
Once every ten years comes the aptert—a day when monk-scientists are allowed to go outside the gates of the community, while curious laypeople can enter. When trouble arrives, putting the world on the edge of catastrophe, it can be prevented only through the combined efforts of the “other” people and the laymen…