Imagine a prison with some ten thousand prisoners, many of them dangerous and, to control them, only a few unarmed employees. Small in number, these employees work in shifts. They are almost prisoners themselves, in a routine of tension, but also of humor and emotion. This prison was all too real. While it was in existence, the Carandiru was the largest prison in Latin America, administered by a reduced number of employees. The documentary shows, from the point of view of these few employees, holding the keys, how the prison operated: the delicate balance in the relationship with the prisoners, affinity among employees, moments of tension and, even, of happiness. These are stories told by former employees, among them, Dr. Dráuzio Varella, author of the book Estação Carandiru. These are the secrets of a place that no longer exists.