The exploits of FBI Special Agents Fox Mulder and Dana Scully who investigate X-Files: marginalized, unsolved cases involving paranormal phenomena. Mulder believes in the existence of aliens and the paranormal while Scully, a skeptic, is assigned to make scientific analyses of Mulder's discoveries that debunk Mulder's work and thus return him to mainstream cases.
As Section Chief Blevins expresses his concern with the direction of the X-Files, Mulder becomes obsessed with solving a case that closely parallels an encounter he experienced as a child: the abduction of his kid sister, Samantha.