Yun Ling, a genius in modern medicine, dies unexpectedly and finds herself transported to another dynasty, where she becomes Yun Linglong, the eldest daughter of the Yun family. The emperor decrees that Yun family's young lady must marry the temperamental Prince Rui, Su Qingyu. Yun Linglong's father, unwilling to let his beloved second daughter, Yun Qingcheng, marry the prince, forces Yun Linglong to marry Su Qingyu instead. Yun Linglong reveals that the poison Su Qingyu is suffering from is extremely rare, and it's not something just anyone could obtain. The antidote is also complicated, but she promises to cure him as long as he spares her life, and after a year, she can divorce him. Su Qingyu agrees.