In an age when gods walk alongside mankind, the world of Eos finds itself falling into darkness. Calamity befalls the human race when malevolent creatures known as "daemons" scourge the land and obliterate armies with seemingly unstoppable brute force. In these dire times, nobles of House Caelum rise to prominence. Owing to their god-given healing powers, which allow them to purge the plague spread by the monsters, they earn the people's trust and allegiance.

With no leader to rule the first human kingdom and guide the masses, the gods fervently seek to fill this vacancy—a man of the Caelum bloodline seems to be a desirable choice. The ambitious and charismatic pragmatist, Somnus Lucis Caelum, is pit against his humble and altruistic brother, Ardyn Lucis Caelum, in competition for the throne. As tensions rise between the rivals and anticipations surge, the fate of the world rests upon one of the two's decisive victory.