: For a broader look at the secrets revealed during this era of the show, the Raymond Reddington Wikipedia page summarizes the "imposter" theory and the role Kathryn played in hiding the truth.
Though it is the Season 7 finale, "Requiem" is one of the most famous episodes in the series, featuring the abduction of Fox Mulder.
While officially the 17th episode of Season 4, "Requiem" is a pivotal origin story often grouped with mid-season highlights. It focuses on the backstory of (Kathryn Nemec) and her history with Katarina Rostova and Masha (Liz).
(Season 4, Episode 17 / Often cited as S4E8 in specific contexts)
Derby Drainage