I’m guessing both of you are already aware of The Gulag Archipelago by Solzhenitsyn but if not it’s his master work and crowning achievement in detailing the history of how the soviet system came to be and gives you a philosophical look at exactly why the insanity happened. One of the biggest takeaways is the clear evidence that the judiciary was the most important branch to corrupt in order to create a totalitarian state. The individual stories of political prisoners and unlucky souls in the gulags are harrowing and mind blowing. Solzhenitsyn was almost assassinated when the book came out.