A woman works as a special makeup artist. Because her heart was broken in the past, she finds it hard to love again and has a cold heart full of sadness. She unexpectedly falls in love with a humanoid robot programmed to be the perfect boyfriend and all the while a top star is competing for her affections as well.

Set during the Goryeo dynasty, Won, crown prince, has a sweet appearance hiding a lust for conquest. He is best friends with Rin, an elegant man of royal descent and Won's bodyguard. When beautiful San, the sole daughter of the wealthiest man in the nation, enters the lives of the two young men, the three at first become friends but a tragic romance ensues afterwards. Based on the novel of the same name by Kim Yi-Ryung.

Scarlet Heart: Ryeo is the remake of Chinese drama Bu Bu Jing Xin that stars IU as a woman who gets time-warped back to the Goryeo dynasty, and becomes involved with a very large family of princes, some of whom are vying for the throne, or her affections, or both.