Su Qingyuan has been betrothed to Crown Prince Xiao Jinyuan since childhood, deeply devoted to him for years. When Xiao Jinyuan fell into danger stranded in Yuezhou, she galloped a thousand miles and sacrificed her purity to rescue the heavily injured crown prince; the red mole on her shoulder is a unique mark belonging exclusively to the two of them. Unexpectedly, Lin Wanqing falsely claimed the merit of saving his life, becoming the crown prince's favorite solely based on the rhetoric about the red mole. Xiao Jinyuan listened only to one side and believed blindly, issuing an imperial decree to break off the engagement with Su Qingyuan, and bestowed her in marriage as wife to Xie Jingheng, the top scholar whose childhood sweet-heart is Lin Wanqing.