As the year 1777 opens, King Jeong-jo enters the second year of his reign, which is consistently under threat from the two opposing Noron and Soron factions. To successfully defend his royal power, Jeong-jo draws upon his courage and his loyal servant Sang-chaek. In a shocking twist, Sang-chaek turns out to be an assassin sent to kill Jeong-jo. But, after witnessing Jeong-jo's capacity to justly rule the people, he confesses his true identity, resulting his banishment. But, as he leaves the palace, his eye catches Sal-soo, the deadliest assassin in Joseon. He frantically returns to the court, only to find Sal-soo in combat with Jeong-jo.