In a world covered in miasma, a floating castle is the last refuge for mankind. The Earth is scarred with beasts mutated by the plague while welkin castle is quarantined from the horrors below.

Lucien, a charismatic politician protected in the castle walls, discovers an ancient book where he learns of the exemplars, weapons that can turn into sentient soldiers.

He joins forces with Rowena, a Revenant determined to find a way to come back to life to raise her living son, and the two reluctantly make a pact to overthrow the Mad tyrant controlling welkin.