Prisons are different south of the Rio Grande. I’m not saying those in the US are a lot of fun, but I suspect most prisoners in Attica or Leavenworth would elect to spend ten years there rather than do two or three in a Mexican or Brazilian slammer. Carandiru in Sao Paolo was a particularly bad one, and this is its story. Basically, the prisoners ran it, the only function of the guards being to prevent escapes. There were places in the prison where the guards didn’t dare go at all. This is the true story of a time in that prison, shortly before a riot, witnessed by a doctor who had free run of the place, protected because the inmates respected and needed him. It’s no secret that the movie ends in a riot, that the army was called in to stop it, and that over a hundred prisoners were killed. The army said they were merely protecting themselves. No soldiers died, or were injured. You figure it out.