Getting inside the mind of a terrorist wasn't difficult at all. Even as children, human beings fabricate elaborate revenge fantasies. We're not a particular species. Check out popular video games.
It would be flattering to call it a modern Dirty Harry, but I think this film deals more with the loss of his wife than the traditional revenge vigilante films.
In the Seventies, a lot of executions via electric chair failed because of technical problems. Seed tells the true story of someone who survived and sought revenge. They buried him alive to make it seem he was dead.
