Set during the Joseon Dynasty, 'Yi San' chronicles the remarkable life of King Jeongjo, who is widely regarded as one of the most visionary and reform-minded monarchs in Korean history. The story follows his tumultuous journey from a tragic childhood—marked by the execution of his father, Crown Prince Sado, by order of his grandfather, King Yeongjo—to his rise as a wise and compassionate ruler. Throughout his reign, Yi San must navigate intense court politics, assassination plots, and factional strife while striving to modernize the nation and improve the lives of the common people. Alongside his political struggles, the drama weaves a deeply emotional romance and lifelong bond between Yi San, his childhood friend Seong Song-yeon, and his loyal bodyguard and confidant Kang Dae-su. Song-yeon eventually enters the royal court as a court lady and later becomes the Royal Noble Consort Uibin, standing by the King's side through immense personal grief and palace intrigue. Directed by the legendary PD Lee Byung-hoon, the series highlights themes of loyalty, justice, and the heavy burden of absolute power.