In a cell inside São Paulo's House of Detention, better known as Carandiru, two inmates have a score to settle. The atmosphere is tense. Another inmate, Black Nigger, a kind of "judge" for settling disputes among prisoners, solves the case in time to welcome the Doctor, who has recently arrived--eager to begin an AIDS-prevention program in the penitentiary. The Doctor is faced with extremely serious problems inside this place, known as Latin America's largest jail: overcrowded cells, decaying facilities, diseases such as TB, leptospirosis, cachexia, and the beginnings of an AIDS epidemic. The inmates have access to neither medical care, nor legal assistance. Carandiru, with upwards of seven thousand prisoners, is a huge challenge for the newcomer. But after working there for a few months he perceives something that will transform him: the inmates, even in this appalling situation, are not demonic figures. In his daily contacts with the prisoners who see him in his makeshift office, the Doctor witnesses solidarity, organization, and above all, a great will to live.