S5E18 · The Pine Bluff Variant

Fox Mulder (David Duchovny), Dana Scully (Gillian Anderson), Walter Skinner (Mitch Pileggi), and several other FBI agents hide in a Washington park to catch Jacob Haley (Daniel von Bargen), the second-in-command of an anti-government militia called the New Spartans. As Mulder and the other agents slowly secretly corner Haley, Haley hands an envelope to another man (Armin Moattar) before running off. Mulder gives chase, but Haley somehow evades capture. The agents then discover that the flesh of the man who was handed the envelope has been eaten away by an unknown toxin.

Scully is frustrated that Haley escaped and questions Mulder as to how it happened, but he dodges her queries. Later, at a counter-terrorism task force led by Skinner and U.S. Attorney Leamus (Sam Anderson), Skinner explains that August Bremer (Michael MacRae), the leader of the New Spartans, is involved in an internal power struggle with Haley. At this meeting, Scully also reveals that the man killed in the park was exposed to some sort of biological agent. Later, Scully follows Mulder and sees him meeting with Haley. When she tries to pursue them, she is surrounded by government agents and brought before Skinner and Leamus, who inform her that Mulder is infiltrating the group as an undercover agent.

Mulder is taken to the New Spartans' secluded hideout, where Haley accuses him of being a government mole. Mulder is tortured until he claims that the group has been infiltrated by a different spy. Elsewhere, Bremer enters a movie theater in Middlefield, Ohio, and exposes its patrons to the biological agent, killing everyone inside. Investigating the scene, Scully becomes confused as to how the contagion was spread, as it is not airborne. Later, Scully meets Mulder at his apartment, where, unbeknownst to them, their conversation about the ongoing mission is recorded by Bremer.

Mulder informs the FBI task force that the New Spartans are planning to rob a bank. Meanwhile, Scully discovers that the biological weapon was engineered by the U.S. government, and is spread by touch. She concludes that Haley wants to break into the bank, not to steal money, but rather to contaminate the money, thereby spreading it to millions of people across the country. She also concludes that the entire scheme was a trap intended to kill Mulder. After the fake robbery, Bremer accuses Mulder of being the mole; Haley, however, counters that Bremer is the real mole.

To further his argument, Bremer plays back the tape of Mulder and Scully that he had made earlier. With power now consolidated, Bremer gives Haley a chance to peacefully leave the group by giving him a set of car keys. Haley agrees to these terms and takes the key. Bremer, along with a muscleman from the group, takes Mulder into a desolate area, where it is implied he will be killed. However, Bremer instead kills the muscleman and lets Mulder go, telling him there's a car waiting for him over the ridge.

Mulder arrives at the bank to find that Scully has managed to have it quarantined, and the contaminated money taken away. They also confront Leamus, suggesting that this entire case was a covert government bioweapons test. Leamus responds that it is part of his job to protect the public from the truth. In the final scene, Haley is revealed to have been killed by the contaminated car keys.