Well, one key event was the planning of the escape by the inmates. They managed to find ways to get around the prison security systems. Another important part was the relationship between the inmates and the female employee who helped them. She provided them with tools and assistance. Also, the actual escape and the manhunt that followed were crucial events in this true story.
The true story of 'Escape to Dannemora' mainly revolves around two convicts. They managed to break out of Clinton Correctional Facility in Dannemora. There were issues with prison staff being involved in the escape plot, which made the whole situation very complex and a big scandal at the time. The story shows how the inmates exploited weaknesses in the prison system and the relationships they built within the prison to make their escape possible.
The two inmates were main characters. I can't recall their names exactly right now, but they were the ones who planned and executed the escape. And of course, the female prison employee who played a big role in helping them escape was also a main character.