Mulder and Scully receive information from Deep Throat about a UFO that was shot down over Iraq and has been secretly transported to the US. However, Deep Throat then intentionally misleads the agents to prevent them from discovering the truth.

When several violent deaths in a small farming community are connected by the destruction of digital devices, Mulder believes that people are being driven to kill by the use of subliminal messages in the digital readouts.

Scully mysteriously appears in a Washington hospital, alive but in a coma, and Mulder must fight to keep her alive in order to find out what happened to her and who did it to her. Meanwhile, Scully fights her own personal battle as she decides whether to stay or go on to the next world.

In a small town in Idaho, a man is killed by what seems to be an invisible elephant. Mulder's investigation into the local zoo, its owners and a local animal rights group uncovers evidence of insidious alien experiments.

Mulder receives an encrypted computer disk containing the defense department's top secret files on extraterrestrial life and becomes a target. Scully takes him to a Navajo family that unearthed a buried secret to decipher the disk.

Scully finds her career with the FBI in jeopardy as Mulder is still missing and the Cigarette Smoking Man is pursuing the stolen files. The Navajo elders find Mulder's body in a cave and perform an ancient ceremony to call the spirit back to the empty vessel.

A.D. Skinner and Scully are at a standoff when Mulder bursts in and discovers that Skinner has the digital tape. Reunited, Mulder and Scully travel to a secret vault inside a mine and find an elaborate filing system of medical records which reveals that Mulder's sister may not have been the first choice for abduction. Meanwhile, Skinner deals with the Cigarette-Smoking Man for their safety.

An investigation into a video of an alien autopsy puts Mulder and Scully in the middle of a conspiracy involving WWII Japanese scientists brought to America to continue their experiments which may shed light on Scully's abduction.

Mulder pursues Krycek (unaware of the alien that has taken over his body) to get back the DAT tape containing the MJ documents. Meanwhile, the shooting of A.D. Skinner uncovers evidence that could lead Scully to her sister's murderer.

Mulder and Scully investigate a series of murders linked to a mysterious device that alters television signals causing paranoid hallucinations. One of them falls victim to it.

The Lone Gunmen reveal the (possibly fake) secret history of the Cigarette Smoking Man to Mulder and Scully; from a young captain in the U.S. Army recruited to assassinate President Kennedy, to becoming the mysterious man in the shadows at the height of a global conspiracy.

Scully's recent failing health is revealed to be an inoperable cancer in her skull, which appears to be common among abductees and she attempts to come to terms with her condition. Meanwhile, Mulder and the Lone Gunmen break into a high-security research lab to find the cure that could save her life.

Scully helps Mulder fake his own death in order for him to go undetected through the Department of Defence and find out the answers to his new questions about the government hoax concerning the existence of extraterrestrial life. Meanwhile, at a joint FBI/DOD inquiry, Scully's attempt to drive out the Conspiracy's informant is halted as her cancer takes a bad turn.

The Cigarette-Smoking Man helps Mulder to obtain Scully's cure and also lets him see his real sister who doesn't turn out to be as happy to see Mulder as he would've liked. In return for this, the Cigarette-Smoking Man asks that Mulder quit the FBI and work for him in the Syndicate where he could have power and respect which Mulder turns down, deciding to stay on the side of justice. While Scully's cure appears to have worked, the Cigarette-Smoking Man faces his own enemies and disappears, presumed dead.

Set in 1989, the story of the founding of The Lone Gunmen is finally told as we see how a straight-laced federal employee, a sex mad AV expert, and a nerdy computer hacker meet Susanne Modeski, a strange woman with evidence of a government conspiracy. When their plan to expose the conspiracy fails and Susanne is captured by a group of men-in-black, led by none other than X, they soon become a paranoid group of government watchdogs.

DNA testing on Emily reveals that she is actually Scully's daughter and Mulder comes to assist her. While Mulder is looking for any information about where and how the girl was born, Scully searches for a cure to Emily's strange illness.

A super-intelligent virus program is let loose on the internet and begins to grow and expand by itself, eventually killing its creator when he tries to eradicate it.

The Cigarette-Smoking Man returns as Mulder investigates the attempted assassination of a young boy with psychic powers who may be the proof that he has looked for all his life.

Mulder goes to the Bermuda Triangle when he learns that the Queen Anne, a British luxury liner which disappeared during WWII, has reappeared in the middle of the Sargasso Sea. Mulder's boat is wrecked and after floating in the water, he is hauled aboard the ship which has just been hijacked by the Nazis searching for the man who will build the atom bomb.

Mulder tries to convince the crew that they have traveled into the future, but evidence further suggests that it is he who is back in the past.

Mulder is thrown in jail at the Area 51 compound but is released when it is discovered that the flight data recorder he stole was a fake. Scully comes to her senses and realizes that the Mulder she sees isn't who he really is and heads back to Nevada to help the real Mulder. Meanwhile, the mechanism that caused the body swap is rapidly snapping back, undoing everything in its wake, and Mulder and his alter ego must race to put themselves back where they belong.

The Cigarette-Smoking Man reveals all the government secrets from the past 50 years in order for his son, Jeffery Spender, to join him in his work. Mulder learns that the final stage of the conspiracy will soon begin with the hybridization of the Syndicate members, and he must stop it from happening. Agent Spender deceives his father and arranges for Mulder and Scully to be reassigned to the X-Files, which doesn't sit too well with the Cigarette-Smoking Man.

While on a stakeout of a Government Defense Convention in Las Vegas, The Lone Gunmen are reunited with Susanne Modeski, the mysterious woman who disappeared ten years earlier when they first met Agent Mulder.

When the bodies of a couple who have been missing for less than a week are discovered to have been reduced to bone, Mulder suggests that recent paranormal phenomena in the area may have caused the accelerated decomposition.

The Lone Gunmen call Mulder and Scully to a virtual reality development lab where they learn that one of the program testers was killed inside the computer generated game environment by the digital image of a woman. Needing to get his yah-yah's, Mulder enters the game to fight the woman, but Scully must step in to save him.

The Cigarette-Smoking Man offers to show Scully the cure for all diseases if she travels with him, but on one condition: Mulder must not know about her trip.

Mulder and Scully return to the town of their first X-Files investigation where a UFO has crashed in the forest. The Cigarette-Smoking Man arranges for Krycek to be released from prison in order for him to make contact with the aliens and begin rebuilding the "Project", while Scully's health appears to be taking a turn.

Newly appointed Deputy Director Kersh organizes a manhunt for Mulder and assigns Agent John Doggett to head the team. Scully and Skinner go along with the investigation but are warned by Kersh that they will be fired if anything is said about aliens. Scully, along with the Lone Gunmen, surmise that the Bounty Hunter is trying to erase all evidence of abductions, and they realize that he may be going after Gibson Praise, who is now living at a school in Arizona. Agent Doggett comes to the same conclusion and his team race Scully and Skinner to the school where they find Mulder trying to kidnap Gibson.

Working without Scully's input, Doggett and Skinner try to stop the mysterious murder spree of a drug-induced religious cult leader, and it becomes clear that the man can enter the dreams of the people he knows and can kill them in their sleep.

Doggett comes upon an old case that Mulder kept secret from Scully and he follows up the investigation, hoping to find a possible connection to Mulder's disappearance.

Shortly after Mulder is buried, Billy Miles is found very dead, but he somehow comes back to life. Skinner and Scully put all their hopes into digging up Mulder and discovering that he too, is still alive. As Mulder lies in the hospital without indication that he is going to fully recover, Krycek comes to Skinner and offers him a vaccine to the virus that has infected Mulder, but the cost of the vaccine is that Skinner has to kill Scully's unborn child.

Mulder's request for reassignment to the X-Files is denied by Kersh, who hopes that Mulder will simply quit the FBI. When a census worker is killed on the White House lawn trying to get information to the President, Mulder gets in over his head trying to discover what the man knew.

Mulder, Doggett and Skinner attempt to fight off the alien replicants, and they find a connection to the conspiracy that leads into the FBI while Reyes and Scully head to a remote farm to safeguard the birth of Scully's child.

Agent Doggett investigates the death of an EPA official after his car is forced off a bridge by a woman he picked up. He asks for assistance on the case from Scully, who has returned to her teaching position at the FBI Academy in Quantico.

Doggett catches up with Shannon McMahon, the woman who the EPA official picked up. She claims to be a super soldier and that the people she has killed were poisoning the water supply, and she wants Doggett to expose the truth.

When pieces of the spaceship beached in Africa resurface, the conspiracy within the FBI attempts to hide the information from the X-Files, especially the one person for whom the pieces have a special significance - Scully. When Doggett and Reyes discover that Scully and her child have been put in great danger, they race to protect her and William from the evil forces pursuing him, and Scully is forced to take drastic measures to protect her child.

Scully is anxious to recover William from his kidnappers and takes matters into her own hands when the FBI's attempts to assist in the investigation are less than helpful. With the help of the Lone Gunmen, Scully discovers terrifying information about her child's captors, and is once again forced to confront the mystery regarding the sinister interest in her son.

The agents ask the Lone Gunmen to help find their friendly foe Yves Adele Harlow after former Area 51 Man-In-Black Morris Fletcher claims she is one of the super-soldiers.

After not knowing Fox Mulder's whereabouts for the last year, A.D. Skinner and Agent Scully learn he's being held for the murder of a military man he couldn't possibly have killed: Knowle Rohrer, one of the government's secret super-soldiers. With Skinner acting as Mulder's defense, people who Mulder has dealt with during his last nine years as an FBI agent testify on his behalf. But the military tribunal isn't interested in the truth.