In 1938 Stalin decided to purge NKVD chief Yezhov, the main reason is that the guy knew too much. However because Yezhov knew exactly how Stalin's methods of purging someone worked, he knew exactly, for months in advance, what was coming. And then..... decided to do nothing about it and just get drunk.
What if Yezhov had thoroughly documented all of Stalin's dark secrets, and when the time of his purge came he defected to the US or another country, leaking out for the world to see (including the USSR) all that Stalin had done?
What would be the outcome?