A modern assassin skilled in medicine and poison transmigrates into the body of a foolish, unloved daughter of the Chancellor's household and is forced to marry the wife-killing Prince Regent. On their wedding night, she discovers him on the brink of death from a poison attack. Pretending to be foolish, she secretly uses acupuncture to detoxify him, only to attract the suspicious prince's attention. When the Empress Dowager serves her poisoned pastries and her wicked younger sister sets a deadly trap, she shoves the poisoned pastries straight into the Empress Dowager's mouth. Later, when the Prince Regent fakes his death to lure the enemy into the open, she exposes irrefutable evidence of treason against the eldest prince and the Chancellor before everyone. But on the eve of the enthronement ceremony, she discovers that her transmigration may not have been an accident.