The drama series chronicles the life of Jang Yeong-Sil, a scientist, engineer, and inventor from the Joseon era. Originating from the lower nobi class, Jang Yeong-Sil catches the attention of King Sejong, who invites him to the royal court. Recognizing his talents, King Sejong provides him with the opportunity to showcase his skills, leading to the creation of various innovations such as astronomical devices, an iron printing press, and a water clock.