The 4th season started airing on the Fox network in the United States on October 4, 1996, concluding on the same channel on May 18, 1997, and contained 24 episodes. Pursued by an Alien Bounty Hunter, Jeremiah Smith takes Mulder to a farm where he finds several girls who are clones of his sister. In the next episode, a really weird one in which I don’t like the ending, the agents investigate the death of an infant with disturbing birth defects, and the trail leads to a clan of inbred, genetic mutants in a small otherwise peaceful town. Mulder and Scully are called in to investigate the unexplained deaths of several African and African-American people whose skin color has turned white as the result of either a rare medical disorder or a bizarre curse.
Next Agents Mulder and Scully investigate a group of bizarre kidnappings in which the only clues are inexplicable photographs. But when Scully is the next intended victim, Mulder must get into the killer’s head. Mulder’s search for an informant inside a cult compound leads Scully and him to one of the cult leader’s wives. What they soon discover is an unexpectedly close connection with the woman – in a previous life they were lovers. After Mulder’s regression scene, he clearly details all of his past lives. Bizarre murders in a hospital’s plastic surgery unit lead Mulder and Scully to suspect a supernatural force may be responsible. Mulder, Scully and Byers meet with Frohike, where he details what may have been Cigarette Smoking Man’s real life. A diplomatic courier carrying deadly cargo involves Agents Mulder and Scully in a dangerous web of intrigue, with Krycek involved, which leads Mulder on a trip to Russia. Scully and Skinner attend a suspicious Senate hearing, while Mulder and Krycek face off in a Russian gulag.
Agent Mulder is haunted by an old case in which young girls were killed and hearts cut from their nightgowns. Soon Mulder becomes suspicious when the killer taunts him with the idea that one of his victims may have been Samantha. Deadly rain in a migrant workers camp sends Agent Mulder and Scully on the trail of a mythical beast — El Chupacabra. The disappearance of a man’s body from a hospital morgue leads Mulder and Scully to investigate the strange circumstances surrounding the man’s death. However, for Scully it will lead to a horrifying revelation. On a solo assignment out of town, Scully meets Mr. Wrong, a man whose tattoo does not want to share him – especially not with Scully. Fear for Scully’s health sends Mulder to investigate the bizarre circumstances that may explain her mysterious abduction two years ago, while Scully takes a more practical course to quell her illness. A murder in a Jewish community leads to the deaths of the killers, forcing Mulder and Scully to determine whether vengeance or larger forces are at work. The mysterious assassination of a high-ranking military official has Mulder and Scully racing against the clock to stop a seemingly unstoppable – and invisible – assassin. While celebrating Scully’s birthday, Mulder learns of Max Fenig’s death in a plane crash. What the agents soon discover is that the circumstances surrounding the crash may have been alien. 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.
Mulder and Scully investigate a murder for which the suspect presents an incredible alibi — that the death was foretold by an old man able to see into the future. A small town is “blessed” by babies being born with tails. Mulder and Scully arrive only to encounter a suspect who proves nearly impossible to identify. Agent Mulder launches a criminal investigation into a bizarre death which he finds has connections to A.D. Skinner. Meanwhile, Skinner makes his own deal with the devil in a desperate attempt to save Scully from the cancer that is taking over her body. Mulder and Scully track a series of murders that lead to a home for the mentally ill and a clue that makes no sense: each victim had a purported warning from the dead. However, while Mulder makes some surprising discoveries, Scully is reminded of her own mortality. Scully is concerned for Mulder’s well-being when he suffers from a memory loss while investigating a case — and is the only suspect in a brutal double murder. Researchers in northern Canada discover what may finally be irrefutable proof of alien existence, but even Mulder is skeptical until sinister agents begin to kill to prevent its revelation, leading to a shocking conclusion.
This season focused heavily on FBI federal agents Fox Mulder’s (David Duchovny) and his partner Dana Scully’s (Gillian Anderson) investigation of an alien conspiracy, which is protected by the mysterious Syndicate. Midway through the season, Scully is diagnosed with terminal cancer, a result of her previous abduction, and Mulder begins to lose his faith in the idea of extraterrestrials. The season ends on acliffhanger, with the purported suicide of Mulder.