You want spoilers?

1. They find some people who bought trillions of cell phone pings
2. They use the data to identify mules who went to non profits and 10+ vote drop boxes
3. They file FOIA to get millions of minutes of surveillance video from voting drop boxes

It's a good investigation. It's boring as fuck. I fell asleep. Go watch it and buy a shit ton of snacks so movie theaters want to play it more, just like I did. But the producer did a pretty shitty job of making it entertaining. 95% of the movie is 4 people sitting at a table talking.