In 1974, a shooting shocks South Korea. Detective Cheol-gu, who witnesses the attack, Jae-hwan, the city desk editor whose coverage is suppressed, and Young-il, a rookie reporter, begin to dig beneath the cover-up. As their pursuit of the truth deepens, they come to confront forces meant to remain unseen.

A true historical drama about King Sejong, the greatest ruler in Joseon history who sought to enhance national prosperity and military power through astronomy, and Jang Yeong-sil, the most remarkable scientist.