"River Dogs" is based upon reported events.Set in Brazil, "River Dogs" tells the story of a band of killers at work in the Amazon, and Paolo Herez, the Interior Protection agent assigned to their case.Paolo's beautiful young wife remembers how her husband had almost died at the hands of these same killers some years earlier, and begs him not to take on the assignment. But there are too many lives at stake for him to refuse.He travels from Rio to central Amazonia and takes up surveillance in a lawless backwater town where he has to fight to gain acceptance into the community. This pays off when the killers arrive at the town to hire pistoleiros. He stays in the background, unrecognized, watching and listening, until learning vital information which has to be relayed back to Rio via phone from a nearby mining town.It is when the killers' paymaster learns that Paolo could ruin his plans that he makes the mistake of trying to kidnap Paolo's wife. She is luckily saved by two off-duty cops, though badly hurt during the kidnap attempt. Paolo is ordered back to Rio, and now he is out not only for justice but also revenge. And from here on in it's fighting fire with fire.He uncovers a collusion between the killers' paymaster and government officials, and sets about extracting information from suspects.Meanwhile, at a remote logging station deep within the rainforest, the manager's deranged wife discovers her husband's "affair" with their housegirl, Danhilla, and takes horrific revenge which only leads to her own demise.Paolo has to leave his wife recovering in the care of her family and travels back to the Amazon with a burning desire to end the killers' rampage.He is captured after a battle between helicopters over an Indian village, taken back to the logging station, which is now the killers' base, tortured and thrown into a cellar. Days later he is saved in the middle of the night by Danhilla, the young housegirl, who had overheard a discussion to kill him.They escape together, fleeing through the rainforest on horseback, and run straight into the hands of a team of Paolo's fellow agents waiting to swoop on the logging station at dawn.Paolo finds himself in a one-to-one fight with his torturer. The man, bleeding heavily, is thrown from the raft upon which they have been fighting, and washed away into a vast floodplain, habitat of man-eating piranha fish.Paolo finds a huge stash of American dollars in the killer's rucksack and as he comforts Danhilla he thanks her for saving his life, rewards her with the cash. As he promises to reunite the young girl with her family in Rio, he tells himself that this had been his last mission. From now on, his wife would come first.