Paramilitary police group in Rio runs the drug dealers out of town, so things should improve, right? Well, the drug trade goes away, but the extra income the regular police were getting in the form of payoffs from the drug dealers also goes away, so they need to find a new way to supplement their income. They do so by muscling their way into every business that is operating in the slums: bottled gas for cooking, satellite TV, jitney buses, etc. Where before they were making 30K a month, now they are making 300K. That would be reals, which are worth about 55 cents today. Our hero finally figures out what is going on and blows the whistle. The coppers don't take kindly to that, so they pull out their guns and we get a real live shooting war. A bunch of corrupt cops end up going to jail, but the governor, who was in cahoots with these guys continues on his merry way. Probably got reelected on a "root out the corruption" campaign.
Wikipedia has an interesting story about the security of this film.