Drama series follows the life Jang Yeong-Sil: a scientist, technician and inventor during the Joseon period. Jang Yeong-Sil was born in the lower class nobi. King Sejong notices his abilities and brings him to the palace. King Sejong grants him a chance to display his abilities. He invents tools like astronomical instruments, iron printing press and a water clock.

• Song Il-gook
• Park Sun-young
• Kim Sang-kyung
• Kim Yeong-cheol
• Kim Ki-hyeon
• Son Byung-ho
• Jung Han-yong
• Jang Kwang