The first X-Files episode that genuinely scared me upon it’s airing in 1994,
Beyond the Sea follows a death row inmate - Luther Lee Boggs - who claims that he is psychic and can lead Mulder to a serial killer in exchange for a lesser sentence of life in prison. Aside from Brad Dourif giving one of the best guest star performances of the entire series with his portrayal as Boggs, the roles of Mulder and Scully are reversed - with Mulder doubting Boggs's claim and the skeptical Scully believing in Boggs’ claimed psychic abilities after she is told that she can communicate through him with her recently deceased father. This is the episode where we start to learn that Scully can be a “believer” under certain circumstances.