Destitute apothecary Lin Chen, in order to save his disabled younger sister, sheltered a five-year-old spiritual fox Bai Ling who came to repay a kindness in a ruined temple. Ling'er used her blood and tears to help him acquire an alchemy system, clear his debts, and even allow his sister to stand again. Yet facing the temptation of immortal cultivation techniques, a luxurious mansion, and a marquisate, Lin Chen tore up his vow, going from begging Ling'er to shed tears voluntarily to drugging and piercing her with needles, forcibly extracting her heart's essential blood. The divine pill stained with resentment caused the city lord to turn into a demon, and the entire city was reduced to purgatory. Until the system settled accounts, his sister died, and the heavenly fox descended, did he realize that the real demon was never the system, but his own endless greed.