This English version doesn’t quite measure up to Oliver Hirschbiegel’s original German film, which itself was based on a novel (Black Box), inspired by a real experiment conducted at Stanford University in 1971. The US Navy funded the study and abandoned it after just six days when things went wrong. The premise involves several individuals who are interviewed and then twenty-four are chosen to participate in an experiment: they’ll be filmed inside a mock prison, where eight will act as guards while the other sixteen become prisoners. The plan is for this to run for two weeks, at which point each participant would receive fourteen thousand dollars. There are guidelines, of course, and if broken, a red light signals the end of the experiment, meaning no one gets paid. Prisoners aren’t allowed to speak unless spoken to, they're given three meals daily that must be finished, and required to exercise for an hour each day. Rule-breaking or disruptive behavior results in punishments “commensurably” within thirty minutes. Physical violence is supposedly off limits—though it happens surprisingly quickly. Perhaps those running the experiment considered these actions equivalent to what prisoners might do. It’s also a condition that if anyone quits, the whole thing is over. Adrien Brody (known for King Kong and Predators) stars as "prisoner" – a man seeking money so he can join his girlfriend in India on a journey of self-discovery—while Forest Whittaker (of Phonebooth and The Last King of Scotland) portrays a quiet, mild-mannered “guard” who still lives with his parents. He befriends Brody during the interview process but becomes completely absorbed by his role and is quickly corrupted by the power it gives him. The two lead actors, both Oscar winners, seem to be taking on less demanding roles, though they don’t overact. The film moves along at a quick pace—ninety minutes total—so there's not much time to consider its problems while you are watching, but those issues become apparent afterward (questions like: who is organizing this experiment? Why the strict and potentially dangerous rules? Why don’t they stop things as soon as violence starts? And why would seemingly straight men be so quick to attempt sexual assault after only five days?). It's an acceptable if unmemorable way to spend ninety minutes.

Source on TMDB