An herb-gathering old man mistakenly breaks into the cave dwelling of a blind snake immortal at Black Wind Cliff, and is forced to offer a daughter to atone for his crime. The pampered younger daughter, Li Jiaojiao, fears disaster and refuses the marriage. To save her entire family, the kind-hearted eldest daughter, Li Wan'er, resolutely accepts the protective heart scale and takes her place in marrying into the gloomy snake lair. Facing the terrifying-looking snake immortal, she consistently treats him with gentleness, and her purely kind heart unexpectedly breaks the snake immortal's centuries-old poisonous curse—turns out he was originally Mo Yuan, a heavenly medical immortal framed by others. The two become a couple, return home to slap the faces of their mercenary relatives, and open the Jishi Hall to practice medicine and save the world, successively defeating corrupt doctors' framing, vicious merchants' harassment, and wicked paths' evil plots, upholding worldly justice with benevolent hearts and medical skills, ultimately reaping a consummate good harvest of kind intentions.