Joseon X-Files - Secret Book (기찰비록 / Gichalbirok)

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 Jeong-Eun) approaches each case with an open mind and secrets of her own.