Chaos reigns in the world, and people and creatures are defenseless against an unknown threat. However, the Vatican has a solution. Father Nicholas, a Catholic priest, is required to pray, forgive sins, and protect his flock—including magical beings living in modern cities. The Twenty-Third is a demon living inside a monk’s body—he must study the human world, smoke on duty, and irritate priests, especially Father Nicholas. Now they are forced to work together and set off on a long and dangerous journey, while trying in advance not to destroy each other.