When a pair of teenage girls attack one another, each believing the other to be a monster, Mulder and Scully find that their investigation could possibly lead back to their long-lost son, William. Then, Skinner goes AWOL when his past comes back to haunt him. As Mulder and Scully try to track him down, their growing mistrust of him reaches its apex. http://x-files.wikia.com/wiki/Ghouli