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.
A serial killer is captured after a three year manhunt, and he claims an evil spirit is responsible for the crimes. When the killings continue as he sits in jail, Mulder's battle with a former colleague gets more heated when he suggests that something more paranormal may be involved.