there's a new documentary called Cold Case Hammarskjold that might be up your alley.
I didn't know much about Dag Hammarskjold, except about the plane crash, and I certainly didn't know there was so much evidence pointing to a murder, but I became interested reading about it.
https://www.timeout.com/us/film/cold...skjoeld
It's by a Danish filmmaker (appropriately), and it's kind of charming in being quite modest, unlike the usual slick Hollywood films. The filmmaker is a stolid, uncharismatic middle-aged guy, narrating his search, with occasional bits of humor, but pretty low-key. But it steadily gathers power and pulls you right along, until I think you end up stunned at all this taking place.
https://www.rottentomatoes.com/m/cold_case_hammarskjold