Yunjo is the dark prince of the country, who always stays in the dark to protect the country without the need for recognition. He fights wars and wins against the enemies under the name and the shadow of his brother, prince Yigang. Then one day, he meets a girl who makes his heart skips a beat and his whole existence turns upside down named Seolyun. What will happen to the man who is used to stay in darkness to follow the voice of his heart? What will he encounter on the way of stepping into the light again and be on the same path with the woman he loves?