“Mysterious Manuscripts” is an episode of the documentary research film “Ukraine. Taking back its history." The authors of the film are investigating the complicated case of the murder of Metropolitan Hryhorii Yaroshevskyi (1872–1923), a Ukrainian by birth. Metropolitan Yaroshevskyi actively researched the history of Ukraine. The results of the investigation into his murder lead to the falsified history of the so-called “Dark Ages,” when the Ukrainian lands were part of the Grand Duchy of Lithuania. Behind the truth of this period lie facts that changed the course of history and explain many modern events.