MULDER'S FORMER MENTOR IN THE BUREAU ENLISTS HIS AND SCULLY'S AID IN A SERIAL MURDER CASE, WHOSE BIZARRE MUTILATION MURDERS CONTINUE EVEN AFTER THE KILLER IS CAUGHT.
Assistant Director Walter Skinner assigns Mulder and Scully to a serial killer case, where Mulder finds his old mentor in charge. Special Agent Bill Patterson of the Behavioral Sciences unit has already caught the killer, but when another murder following the same pattern occurs, he needs the "cracked genius" of Fox Mulder to solve the case. Was confessed murderer John Mostow working with an accomplice, who now continues the killing spree? Or was the murder committed by a copycat? Patterson and Scully hope to resolve the question either way, but Mulder believes in a third possibility: demonic possession.