In an age where gods coexist with humans, the world of Eos is descending into darkness. When terrible monsters known as "daemons" roam the world and annihilate armies with apparently unstoppable physical might, disaster strikes the human race. Nobles of House Caelum rose to prominence during these difficult times. They gain the people's confidence and devotion due to their god-given healing skills, which allow them to cleanse the sickness spread by the monsters. With no one to rule the first human kingdom and shepherd the people, the gods are eager to fill the void—a man of the Caelum family appears to be a desirable candidate. Somnus Lucis Caelum, the ambitious and charismatic pragmatist, is pitted against his modest and altruistic brother, Ardyn Lucis Caelum.