As a result of an unknown catastrophe, most of Earth's population is quickly degrading, people are becoming like beasts by the day. They are called thiriomorphs. Those who survived protected themselves as they could with what they had. They built a giant city in the skies, others dug themselves underground, others still built a city on water. Those communities were relatively safe, the outcasts were cursed to walk the earth, or to become prey.
The heroes of the story are looking for their way in a world filled with monsters - hunters in the purest sense of the word, the perfect killing machines that even nature's design couldn't dream of, and it seems that there was nothing as ruthless and efficient like them on earth. Over the course of the story, the characters of the story show us that there is nothing as dangerous as man on this planet, and there is nothing more beastly than a human being.