17. Check Your Head

S4 E17: The team members search for Rachel an agoraphobic advice columnist who had not left her apartment in two years. While casing her apartment for clues, they ponder the relevance of a walkie-talkie, a box of bullets and a stack of letters from an array of prisoners and oddballs who were seeking her advice and/or threatening her. The investigators then theorise that she may have fallen prey to an obsessed fan.