This episode focuses on Agent John Doggett and agent Monica Reyes trying to figure out what happened to an older couple that was murdered out in the middle of the country. Agent Reyes believed they were possessed by Satan himself, but Doggett did not want to believe that that was actually possible. It ended up being that Doggett took it really personal and ended up lashing out that it was impossible.
A patient who chopped up people into pieces was apparently possessed by Satan. This episode was a really good episode because it combined a lot of great thing people love about the x-files.