A seemingly unmotivated murderer, who can apparently talk his victims into killing themselves is on the loose and it is up to Mulder and Scully to study the clues left to them by the person and capture him.
After a serial killer, who claims to have killed people under the influence of a demon, is arrested, the murders continue. Meanwhile Mulder, who believes that the demon might have picked someone new, goes neck-deep in the investigation.
A furious pursuit of Agent Mulder is underway, and more importantly, the government wants the data tape he carried. Agent Scully, against all odds, searches to uncover his whereabouts, persisting that he is alive when all others deny it.
Reports of foxfire on a field in Dudley, Arkansas lead Mulder and Scully to a bizarre situation regarding the townsfolk. Employees of the Chaco Chicken Corporation are displaying bizarre behavior, and the death rate is slowly increasing.
When some people on a ship are rescued, it is discovered that they are aging and later, dying. Mulder takes it upon himself to investigate the ship, which he believes has been the target of Philadelphia Experiments.