Season 4, Episode 1: Herrenvolk
Original Air Date—4 October 1996
The continuing search for Jeremiah Smith leads Scully to uncover encrypted data files whose purpose is not yet known. Being closely hunted by an unknown assassin, Jeremiah leads Mulder to a secluded farm in rural Canada while men in suits determine Mrs. Mulder's fate.
Season 4, Episode 2: Home
Original Air Date—11 October 1996
The remains of an infant suffering from an uncharted amount of birth disabilities are uncovered in a field in rural Home, Pennsylvania. The only suspicious residents are three brothers who have lived on their family farm for twenty-some years. They live there alone. Or do they?
Season 4, Episode 3: Teliko
Original Air Date—18 October 1996
Several African American men in Philadelphia, PA have gone missing, and one of them turned up dead under mysterious circumstances. All pigment in his skin was lost, and the cause of death may have a connection to an ancient African tribal monster who stalks the night for its prey.
Season 4, Episode 4: Unruhe
Original Air Date—27 October 1996
An intended passport photo for a missing woman develops warped and twisted, showing her terrified and surrounded by beings. With a little investigation, Mulder develops a theory that the kidnapper of this woman has the power to psychically display his thoughts on film.
Season 4, Episode 5: The Field Where I Died
Original Air Date—3 November 1996
Agents Mulder and Scully investigate a suspicious religious cult, which inadvertently draws Mulder into recalling a past life, in the field where he died.
Season 4, Episode 6: Sanguinarium
Original Air Date—10 November 1996
The bizarre, perhaps ritualistic death inside Greenwood Memorial Hospital's Aesthetic Surgery Unit is cause for alarm. Though head practitioners are at first unwilling to help Mulder and Scully with their investigation, several more 'possession killings' force them to.
Season 4, Episode 7: Musings of a Cigarette Smoking Man
Original Air Date—17 November 1996
Mulder and Scully are called to meet with The Lone Gunmen. It is there that Frohike reveals an uncovered history of the infamous Cigarette-Smoking Man. The story told involves his desperate attempts to live a worthy life while continuing to conceal and change American history.
Season 4, Episode 8: Tunguska
Original Air Date—24 November 1996
When a man carrying a sample of the mythical black oil into the US is detained and the sample is released, the hierarchy involved in its concealment must act. Led by a revived and vengeful Krycek, Mulder and Scully seek to find its origin, its purpose, and perhaps its cure.
Season 4, Episode 9: Terma
Original Air Date—1 December 1996
Called upon to disclose Agent Mulder's current whereabouts, Scully must stall the hearings until further understanding of the mysterious "black cancer" is revealed. Mulder, in the mean time, must escape a Russian prison camp, or be subjected to the "testing" until he dies.
Season 4, Episode 10: Paper Hearts
Original Air Date—15 December 1996
A recurring dream of Mulder's leads him to discover the 14th victim of a serial killer whom he caught years before as a detective. The murderer takes heart-shaped fabric from each of his young girl victims' clothing, and insists Mulder go on a goose-hunt to find the final two missing girls - one of which may be his sister.
Season 4, Episode 11: El Mundo Gira
Original Air Date—12 January 1997
White flashes of lightning followed by yellow rain in southern California north of the border give new life to an old Mexican folk-tale of El Chupacabra, a gray-skinned being whose victims decompose fast. Are the stories true, or is there simply a new viral pathogen in the world?
Season 4, Episode 12: Leonard Betts
Original Air Date—26 January 1997
After an ambulance accident leaves Pittsburgh, PA's EMT of the Year Leonard Betts without a head, and what's left of his body seems to walk right out of the morgue, Mulder and Scully investigate. They find what may be evidence of evolution from man to something... cancerous.
Season 4, Episode 13: Never Again
Original Air Date—2 February 1997
Agent Mulder has taken a week-long vacation and it's up to Scully to track several Russian war veterans in Philadelphia, PA. She arrives, upset and disturbed, but soon is distracted by a single man with a tattoo. The tattoo, unfortunately, has a cynical mind that is eager to kill.
Season 4, Episode 14: Memento Mori ♥
Original Air Date—9 February 1997
The horrible truth behind Scully's illness is revealed: she has cancer and may die. Such has been the fate of a dozen other women who, last year, introduced themselves as abductees and made claims of being with Dana on an alien space ship. Mulder must find a cure, and fast.
Season 4, Episode 15: Kaddish
Original Air Date—16 February 1997
Three teenage murder suspects involved in the death of a Jewish store clerk in Brooklyn, New York, are in danger, for it seems that the murder victim himself is vengefully claiming their lives. Mulder and Scully work to solve the case, but their suspect may not be alive enough for them to take in, or stop.
Season 4, Episode 16: Unrequited
Original Air Date—23 February 1997
The execution of an honored military general by a seemingly invisible assailant receives the attention of Assistant Director Skinner and a special task force including Mulder and Scully. The feds have less than twelve hours to find the mysterious man before more generals are killed.
Season 4, Episode 17: Tempus Fugit
Original Air Date—16 March 1997
Mulder and Scully investigate a plane crash in New York state. The crash appears to be UFO caused because one of the passengers was Max Fennig, an alien abductee, who Mulder and Scully know from a previous encounter. The agents work against the military which attempts to cover up what really happened to that flight.
Season 4, Episode 18: Max
Original Air Date—23 March 1997
The investigation continues for agents Mulder and Scully of the apparent downing of Flight 549 by a UFO. They encounter deadly opposition from the military which continues to cover up the truth of incident.
Season 4, Episode 19: Synchrony
Original Air Date—13 April 1997
A mysterious old man is killing scientists working on the development of a cryobiologic compound. He freezes them to death with this same compound that doesn't even exist yet.
Season 4, Episode 20: Small Potatoes
Original Air Date—20 April 1997
Five unrelated women in a small town give birth to babies with small tails. The prime suspect is a man who can shape shift into whomever he wants.
Season 4, Episode 21: Zero Sum
Original Air Date—27 April 1997
A swarm of bees mysteriously kill a postal worker in an enclosed restroom. Assistant Director Skinner covers up the evidence. Mulder investigates Skinner's apparent involvement with the crime.
Season 4, Episode 22: Elegy
Original Air Date—4 May 1997
Several women are killed in the same manner within blocks of each other. One of the dead women's ghost is seen by the proprietor of a bowling alley attempting to communicate. The cryptic message "She is me" is found where the apparition appeared. It's also apparently the dying woman's final words.
Season 4, Episode 23: Demons
Original Air Date—11 May 1997
Mulder wakes up in a strange motel room with blood on his shirt and not knowing how he arrived there. A double murder has been committed with Mulder's gun. Mulder and Scully attempt to clear Mulder's name while finding out what is causing Mulder's memory lapses and blackouts.
Season 4, Episode 24: Gethsemane
Original Air Date—18 May 1997
Mulder is given an opportunity to obtain irrefutable proof of the existence of extra-terrestrial beings. At the same time, Scully deals with her cancer. Michael Kritschgau, a Department of Defense employee, later gives Mulder information that turns Mulder's beliefs about extra-terrestrial life upside down.