There are those who say that we all carry a monster inside us and this movie, which is based on real events, seems to give the reason to who makes that statement. Here, it all starts with an experiment in a university.
The university is Stanford and the professor who designs the experiment is Dr. Philip Zimbardo, in the seventies, becoming one of the most famous social experiments of all time.
What the teacher does is to simulate a jail with his students. Some will be prisoners and other jailers, so you can see how people behave in these situations.
The teacher, and everyone, was surprised when he saw that the jailers became sadistic people, who enjoyed the pain of others, while the prisoners became very submissive people, who did not oppose the abuses they committed on them Those who were his classmates.