A tragic accident leaves an ambitious prosecutor with the mind of a child — forcing him and his mother to embark on a journey to heal their relationship.

A fusion historical drama that combines romance and legal heroes, and contains a fictional story based on the motif of Gyeongguk Daejeon.

Set in 1398. Kim Min-Jae (Shin Ha-Kyun) is the supreme commander of the Joseon Dynasty. He falls in love for the first time and for that woman he takes risks. Yi Bang-Won (Jang Hyuk) is the King’s son. He helped his father setup the Joseon Dynasty era, but he was not picked as the Crown Prince. He still holds ambitions of becoming the King one day. Jin (Kang Ha-Neul) is Kim Min-Jae’s son and the King’s son-in-law. Due to his position as the King's son-in-law, he is unable to take part in politics and only seeks out pleasure.

A servant falls in love with a girl whom his master also desires. Although the girl loves the servant, she also longs to improve her station in life.