No one in modern-day Seoul believes in the old fables anymore, which makes it the perfect place to for Gu Miyoung and her mother to hide in plain sight. Mihoung is a Gumiho, a nine-tailed fox, who must eat the souls of men to survive. She feeds every full moon-eating the souls of men who have committed crimes, but have evaded justice. Her life is upended when she kills a dokkaebi, a murderous goblin, in the forest just to save the life of a stupid boy. But after Miyoung saves Jihoon's life, the two develop a tenuous friendship that blooms into romance forcing Miyoung to choose between her immortal life and Jihoon's.