This is a Brazilian movie that centers around SWAT teams that are meant to battle drug overlords who control neighborhoods and slums.
Within a prison that holds all the different drug lords, a rebellion quickly escalates where all the drug lords kill each other leaving the city without anyone to control it.
Dirty cops quickly see the opportunity and start to run the slums as if they were the drug overlords.
Dirty cops are taken down when the head of the SWAT teams finds out about their hidden scheme. He takes out all the dirty cops and all the government officials.
The movie is driven more by corruption in the police department and government officials then by action or gun fights.
The ending kind of leaves you feeling like nothing is really changed. Certain evil men are dead, but in their place others rise to replace them.
Perhaps that is the point of the whole movie.