Washington Post reporter Reel's source is a non-fiction account of the events surrounding attempts to commercially exploit the Brazilian Amazon. The law states that if even one indigent is still living in any given piece of land, it must be preserved. One such was found in 1996, and investigations turned up the sinister revelation that the entire rest of his tribe had probably been murdered by corporate interests, and that his own life was obviously in danger for the same reasons.
Mark Bailey, co-writer of the documentary Last Days In Vietnam (2014), penned the adaptation, and the film is being set up independently with Doug Liman (Edge Of Tomorrow) among the producers. Haggis has yet to sign on the line, so clearly there is much to be worked out. But if you want to give yourself a primer while you wait, Reel's book is published by Scribner.