18th Century, France. Lia de Beaumont, loyal servant of Versailles and its King, Louis XV, is found dead in the river Seine. Floating inside a coffin, on which the word "Psalms" was written, her body had been poisoned by mercury, thus preserving decay. According to the Church, the soul that belonged to a corpse incapable of being consumed by the soil will forever wander in the human realm, unable to go to Heaven. (myanimelist.net)