I recommend two films both Russian:
1. “The Chekist”
Fiction but these people existed, a out a true Bolshevik believer member of the Cheka who realizes after arresting and executing 100s of people. They weren’t enemies of the revolution, they were just ordinary people. Maybe the enemies never existed, certainly didn’t exist in the numbers his superiors said. He goes mad. Its very a “Crime and Punishment “ style film. Grim, grim film!
2. “The Admiral”
Story of the Artic explorer & WWI naval hero later a major leader of White Russian forces - Admiral Wrangel. The story has a Greek tragedy feel to it. Remember at one time (not that long ago!)saying anything positive about Wrangell would get a reservation in the Gulag.
What i find very interesting about these films is the timing. They came out only a few years after the collapse of the USSR.
Seen The Chekist, the most depressing film ever made.
I would also recommend “The Inner Circle”.