Joseon X-Files: Secret Book is based on cases detailed in the Annals of Joseon History with a bizarre twist; these incidents incorporate mysterious, supernatural elements that cannot be explained through science. Kim Hyung Do is an inspector of the state whose single-minded focus on his investigations into administrative misdeeds bring him into direct contact with these strange mysteries. Heo Yoon Yi is a government employee who aids him and attempts to understand these scientific impossibilities with an open mind, in contrast to his cynicism.
- Drama: Joseon X-Files: Secret Book (English title) / Secret Investigation Record (literal title)
- Revised romanization: Gichalbirok
- Hangul: 기찰비록
- Director: Kang Kyung-Hoon
- Writer: Kim Eun-Suk
- Network: tvN
- Episodes: 12
- Release Date: August 20, 2010 – October 29, 2010
In this Joseon-era alternate history strange, possibly alien phenomena are secretly recorded by people within the government. Inspector Kim Hyung-Do (Kim Ji-Hun) finds himself working with this group as he hopes to uncover the truth that led to his mentor’s death. While he eschews superstition and seeks logical, realistic explanations fellow investigator Heo Yoon-Yi (Lim Jung-Eun) approaches each case with an open mind and secrets of her own.