After several men in a prison die of a mysterious illness, Scully tries to discover the cause while Mulder attempts to find two escapees who could potentially spread the disease.
In the rain forest of Costa Rica, entomologist Robert Torrance stumbles upon a decomposing boar carcass covered with dark purple pustules. As he extracts an insect from one of the pustules, it erupts, spraying him with fluid. By nightfall, the scientist himself has developed the boils and tries to radio for help. When a group of soldiers arrive to rescue Torrance the next morning, he is found dead.
At a prison in Dinwiddie County, Virginia, an inmate -- also named Robert Torrance -- gets a package containing a boil-covered piece of meat. He develops the boils and dies thirty-six hours later. Two other inmates, Paul and Steve, escape in a laundry cart after being sent to clean Torrance's cell. FBI agents Fox Mulder and Dana Scully are sent to help the U.S. Marshals find them. They note that the FBI doesn't normally investigate prison escapes, and become suspicious as the prison is quarantined by the CDC and the National Guard.
Mulder leaves with the Marshals to hunt the fugitives, while Scully remains behind to investigate the situation in the prison. She learns that the lock-down population is infected with an exceedingly deadly contagion. She also finds a pile of dead inmates in body bags, stored for incineration in the prison's boiler room. Scully cuts open Torrance's body bag and examines his corpse, but Dr. Osbourne, a member of the CDC hazmat team, tries to stop her. A pustule on Torrance's body erupts in Osbourne's face, causing him to flee the room.
The fugitives kill a man at a rest stop and steal his RV. They stop at a gas station where Paul calls his girlfriend, Elizabeth, looking for shelter. The station's clerk finds Steve, who has become infected with the contagion, in the restroom; he is knocked unconscious by Paul. Scully calls Mulder after the Marshals raid the gas station, and tells him that if the fugitives aren't captured, the contagion could spread into the population. Mulder sees a CDC biohazard team arrive at the scene, forcibly taking away the clerk in a helicopter.
Paul arrives at Elizabeth's house, where she tends to Steve, who is in the late stages of his infection. One of Steve's pustules erupts in her face, killing him. At that moment, Mulder and the Marshals raid the house. They arrest an infected Elizabeth, but find Paul missing. Meanwhile, Scully traces Torrance's package to Pinck Pharmaceuticals, a major drug developer. She also finds an insect in the body of another prisoner. Dr. Osbourne comes forward and reveals that he really works for Pinck Pharmaceuticals rather than the CDC.
Osbourne, who has become infected, identifies Scully's insect as Faciphaga emasculata, which produces a dilating enzyme that Pinck is researching. But it also carries a parasite that attacks the human immune system; its reproductive cycle develops boils that contain the insects' larvae, which burrow into any hosts exposed to the boils when they erupt. Osbourne claims that F. Emasculata and its contagion were deliberately introduced into the prison by Pinck as an experiment. Dr. Osbourne tells Scully that since she was next to him when he became infected, she may have contracted the contagion too.
Mulder confronts Walter Skinner and The Smoking Man, believing that he and Scully were deceived into taking this case without knowing about the contagion. Mulder is adamant that the public should know the truth about this potential health crisis. The Smoking Man tells Mulder that public knowledge of the truth will create mass panic, and will do more harm than good. "You control the disease by controlling information", he says. Mulder tries to take his case to Scully, but she too says that exposing Pinck's activities may result in a deadly hysteria. For Mulder, Paul is the only remaining proof of the company's crimes.
Mulder and the Marshals finally catch up and surround the infected fugitive at a bus station. A sniper bullet ends the man's life before Mulder can get him to surrender.
SEMICOLON-SEPARATED LIST OF ITEMS/LOCATIONS REFERENCED IN EPISODE (BUT NOT LINKED TO IF ALREADY LINKED IN SUMMARY OR GUEST STARS SECTIONS)
Cast and Characters
- Alvin Sanders (Bus Driver) previously played Deputy Sheriff Jason Wright in The X-Files episode "Fallen Angel".
- Chilton Crane (Mother at Bus Station) previously played Margaret Hohman in The X-Files episode "Miracle Man".
- Charles Martin Smith as Dr. Osborne
- Dean Norris as US Marshal Tapia
- John Pyper-Ferguson as Paul
- William B. Davis as Cigarette Smoking Man
- Angelo Vacco as Angelo Garza
- Mitch Pileggi as Assistant Director Walter Skinner
- Morris Panych as Dr. Simon Auerbach
- Lynda Boyd as Elizabeth
- John Tench as Steve
- Alvin Sanders as Bus Driver