|The X-Files episode|
|Original Airdate:||November 18, 1994|
|Date(s):||November 13, 1994|
|Written by:||Howard Gordon|
|Directed by:||David Nutter|
When a moving shadow appears on a video transmission from a volcano, a volcanologist asks Mulder and Scully to investigate the incident.
Agents Mulder and Scully are recruited by Dr. Adam Pierce to accompany him into Mount Avalon, to investigate the death of a colleague of his – a seismologist named Erickson. Pierce left the project a number of weeks ago, after arguing with project leader Daniel Trepkos. Mulder is concerned about Scully, considering her recent return from her abduction, but she is insistent that she is ready to return to work. The three of them head to Mt. Avalon. While Pierce investigates the condition of the project's satellite equipment, the agents meet the other project members – engineer Jason Ludwig, systems analyst Peter Tanaka and graduate student Jessie O'Neil. The three of them tell the agents that Trepkos has gone mad and disappeared. Soon afterwards, Pierce is murdered by Trepkos outside.
Mulder looks at Trepkos' work, finding references to a new silicon-based lifeform existing inside the volcano. Tanaka shows signs of being seriously ill but refuses any help from Scully. When he starts convulsing, the agents try to take him out on a stretcher but he runs off into the woods, dying when a tentacle bursts out of his throat. Performing an autopsy, Scully believes that spores grew inside Tanaka's body but eventually outgrew his body, resulting in his death. Mulder contacts the CDC, to have them evacuate and quarantine the site. Mulder and Ludwig head into the volcano in search of Trepkos, who kills Ludwig with a flare gun and then burns his corpse.
Based on her research, Scully believes that the spore dies soon after exposure to the air and that one would have to be right next to it when it leaves its host for someone to be infected. Trepkos tells Mulder that Erickson pulverized a rock found in the volcano, resulting in them all being infected with the spore. Realizing that Scully (who is alone with O'Neil) may be at risk, Mulder convinces Trepkos to let him go and help her. O'Neil, with the spore about to burst from her throat, handcuffs herself to Scully. Scully manages to save herself by pushing O'Neil into another room and closing a door between them, just before the spores exit her body. Mulder and Trepkos arrive soon thereafter. Mulder and Scully enter a month-long quarantine. Trepkos, who Mulder didn't tell the CDC survived, heads into the volcano with O'Neil's body.
- This episode was inspired after the success of "Ice" from the previous season.
- The silcon-based fungi which influences its hosts into infecting others has a real-life carbon-based analogue; Cordyceps.
- Bradley Whitford as Dr. Daniel Trepkos
- Leland Orser as Jason Ludwig
- Shawnee Smith as Jessie O'Neil
- Tuck Milligan as Dr. Adam Pierce
- Hiro Kanagawa as Peter Tanaka
- David Kaye as Reporter
- David Lewis as Vosberg
- Torben Rolfsen as Technician