The X-Files · Season 5 · Episode 19

“Folie a Deux”

Aired Monday 11 May 1998

Mulder is held hostage inside an office where a man claims his boss is a monster and has clouded all their minds while he turns them into zombies one by one, which is disbelieved until Mulder opens his mind and allows himself to see it too.

S5 E19 discussion