The story of the infamous Stanford Prison Experiment, a psychological exercise designed to examine the nature of good and evil. In the summer of 1971, a group of American students volunteered to adopt the roles of prisoners and guards in a specially controlled environment - the experiment was terminated after less than a week when it became clear that the participants were being adversely affected.

The prisoners start to pick off weak guards, the most powerful prisoner is sentenced to solitary confinement, and the guards rumble an attempted break-out.

A new prisoner arrives, a master set of keys is stolen, and the two most forceful prisoners come head-to-head in a showdown for leadership.

The oppressive conditions are wearing down the patience of some of the prisoners, whilst the anxiety of the guards is mounting. A reformed crack addict and an Evangelical christian form an unlikely alliance. And the guards find themselves taken by surprise when three prisoners launch a nighttime revolt.

Twelve prisoners and guards join together to form a new and just society but after only a few hours four of them launch a bid for power that shocks and appalls their fellow inmates.