Synopsis: Mulder and Scully are sent to Chicago after after a telemarketing firm receives anonymous threats.The company is particularly concerned as they had an employee go postal in a different office and wants to avoid another dangerous incident.
"Folie à Deux" is the nineteenth episode of the fifth season of American science fiction television series The X-Files.
It was written by Vince Gilligan and directed by Kim Manners.
The episode originally aired on May 10, 1998 in the United States on the Fox network.
The episode is a "Monster-of-the-Week" story, a stand-alone plot which is unconnected to the series' wider mythology, or fictional history.
Walter Skinner (Mitch Pileggi) orders Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) to go to Chicago to do a threat assessment of a taped manifesto that mentions Vinyl Right, which has seen a violent incident at its Kansas City offices.
Mulder suspects that the case is a deliberate waste of time and tells Scully not to accompany him.
During his meeting with Pincus, Mulder learns that the tape was sent to a local radio station with a demand that it be played twenty-four hours a day; on the tape, a man – later revealed to be Lambert – claims that a monster "hides in the light" and stalks employees at Vinyl Right.
Mulder calls Scully and asks her to find past X-Files containing the phrase.
The episode earned a Nielsen household rating of 11.0, being watched by 17.63 million viewers upon its initial broadcast. The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files.