Suspicion arises that someone at the FBI, possibly Assistant Director Skinner, is responsible for Scully's contraction of a fatal disease.
The future of the X-Files is endangered as Scully lingers near death, while the Cigarette-Smoking Man comes forward with an offer to save her life.
Flashbacks to 1989 show the genesis of the Lone Gunmen and recalls how Mulder began his quest; guest Richard Belzer.
Mulder and Scully find themselves stranded in the woods with a deadly predator while on their way to an FBI convention in Florida.
5X05 - The Post-Modern Prometheus
Mulder and Scully follow the trail of a modern-day Frankenstein after responding to a letter from a single mother in a small town.
Scully returns home for the holidays, and begins to have dreams which seem to be connected to a murdered woman's daughter.
Scully tries to protect a girl from the men responsible for her parents' deaths, and Mulder is drawn into a deadly confrontation while probing the girl's origin.
Mulder and Scully race to prevent an old adversary and recent prison escapee from taking revenge on Mulder.
Mulder and Scully fear a greater evil lurks behind the murder of a man whose teenage son is a suspect in the crime.
While vacationing in a coastal town in Maine, Scully meets a girl with the ability to make people injure themselves.
The murder of a computer programmer leads Mulder and Scully to the discovery of a sentient computer program loose on the internet that has targeted its creator and is trying to find the Kill Switch, a series of viruses he wrote to kill it.
Mulder and Scully try to explain their roles in a twisted killing that occurred while they were investigating a case in Texas.
Scully confronts a new threat to her life as Mulder probes a series of horrific mass killings, which leads him to evidence of extraterrestrials.
Mulder is drawn into a dangerous confrontation with creatures that could expose the conspiracy surrounding extraterrestrials.
Mulder questions a former FBI agent (Darren McGavin) about an X-file case from the 1950s which may have involved his father.
Mulder (David Duchovny) disbelieves evidence that implicates a blind woman (guest star Lili Taylor) in a murder. With Gillian Anderson and Blu Mankuma.
At the request of a priest, Scully probes the death of a girl with disabilities and uncovers a supernatural mystery.
5X18 - The Pine Bluff Variant
The agents investigate a group of anti-government terrorists who are experimenting with biological warfare, and Scully notices a change in Mulder's behaviour.
Scully and Mulder meet a delusional man who is convinced his boss is a monster and is willing to prove it.
The agents are drawn into an investigation following an attempted assassination, while someone from Mulder's past conflicts with Scully.