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"Kill Switch" is the eleventh episode of the fifth season of The X-Files. It premiered on the Fox network on February 15, 1998. The episode was written by William Gibson and Tom Maddox, and was directed by Rob Bowman.

Kill Switch is a "Monster-of-the-week" story, independent of the series' mythology arc.


The brutal murder of a renowned computer programmer leads Mulder and Scully to investigate an artificial intelligence program loose on the internet that has begun evolving on its own.


Several heavily-armed crack dealers receive an anonymous telephone call alerting them to the whereabouts of a hated enemy. The men all converge on a diner, but none find their target. Two deputy marshals receive a similar anonymous tip, alerting them about a Colombian fugitive in the same diner. The marshals enter the diner and order everyone onto the floor. Drug dealers draw their weapons and a fierce gun battle ensues.

As the agents observe the aftermath of the shoot-out, Mulder pulls a tarp off the face of Donald Gelman, one of the co-inventors of the Internet. Gelman had been working at his laptop inside the diner when the shooting broke out and became trapped in the cross-fire. Mulder sneaks Gelman's laptop under his jacket and brings it back to Scully's car. He finds a blank CD in the laptop drive, which when placed inside Scully's CD-player emits music - "Twilight Time" by The Platters - while the vehicle's lights flash in rhythm.

Puzzled, Mulder brings the CD to the Lone Gunmen for further analysis. When they are unable to crack the disc's security code, Scully suggests they check Gelman's e-mail log. They find a message containing a standard ID number for a shipping container. The message is signed by someone named Invisigoth.

The agents track the number to a container yard. A figure springs from the darkness, zaps Mulder with a stun-gun, and runs off into the night. Scully apprehends the suspect, Esther Nairn and escorts her back to the container, which is brimming with sophisticated computer equipment. Esther's attention is diverted to one of the monitors. She tells the agents that an armed Department of Defense satellite has locked onto their location. Despite the farfetchedness of the tale, Mulder convinces Scully they must leave the area immediately. Shortly thereafter, a strange green light descends from the heavens and destroys the shipping container.

Mulder concludes that Donald Gelman realized his lifelong dream: the construction of a sentient artificial intelligence, a computer program with its own consciousness. Esther confirms Mulder's suspicion, describing how Gelman unleashed the program onto the Internet so it could evolve—much like the primordial slime from which mankind evolved. She tells the agents that the AI monitors all communication, and will destroy her the moment it locks onto her location. Esther also reveals that Gelman was in the process of creating a special virus program, nicknamed "Kill Switch," that would hunt down and destroy the rogue system. Instead of simply destroying Gelman with a laser from above, Esther is convinced it killed its creator with a dozen crack dealers in an effort to show off its sense of humor. She also believes the virus is holed up on a computer somewhere—and the only way to kill it is to find and destroy its safe house.

By accessing government files, Mulder locates a suspicious T3 line, one that would be needed by the AI to access the Internet. He traces the cable to an abandoned farm on which sits a trailer. Meanwhile, Esther gets the jump on Scully and forces her at gunpoint to drive to an isolated location where she hopes to find one of her colleagues, a man named David Markham. Esther exits the car and begins crying at the site of a demolished house. During her absence, Scully manages to unshackle her handcuffs. Esther gives Scully back her gun and asks her to "put her out of her misery." Esther then admits to Scully that she and David had planned to upload their consciousness and enter the AI. But Gelman forbade the idea. Mulder rings the doorbell on the trailer with the T3 link but receives no reply. Unbeknownst to him, several thermal-imaging cameras are watching him and the doorbell is actually a thumbprint scanner which discovers his identity by running it through a computer. Mulder instead manages to make a hole in the bottom of the trailer and breaks in. Inside he discovers David Markham's body, his face concealed by a virtual reality mask. Removing the mask, Mulder finds Markham is dead. Suddenly, several crab-like droids spring from the jungle of cables and constrain Mulder, putting him in a device similar to Markham's. Sparks fly around Mulder and he passes out. Mulder experiences strange visions involving sexy nurses in a 1940s style hospital who threaten to amputate him, limb by limb, unless he reveals the location of Kill Switch. Meanwhile, the AI pinpoints Scully and Esther in their car near a turntable drawbridge. The pair become trapped and, at Scully's urging, Esther tosses the laptop into the water. Moments later, a green laser blasts the water.

Scully and Esther climb into the trailer where Mulder is bound by the crab-droids. Several of the robotic creatures attack, and Scully dispatches them with her handgun. Scully finds Mulder, his head encased in the virtual reality mask (the source of his strange visions). The AI's screen shows that it is now targeting the trailer. Esther produces the CD, and Scully gives the AI what it wants, inserting the disk into a drive. The targeting system stops. The AI releases Mulder, and Scully drags him outside. Esther accesses a keyboard and tries to make contact with the AI, which might already have David's memory and consciousness. She also restarts the targeting system in the process. When Scully reenters the trailer, she finds Esther wearing the virtual reality helmet, the body of her beloved David nearby. Esther tells her to leave, and Scully races from the trailer, as Esther instructs the AI to upload. Moments later, the green laser destroys the trailer. When Mulder recovers, he tells Scully that Esther's consciousness may have joined the AI.

Meanwhile, in a trailer park, two teenagers are playing catch with a ball when one of them accidentally throws the ball over a fence next to a seemingly ownerless trailer. As one of the teenagers gets the ball and climbs back over the fence, a thermal imaging camera on the top of the trailer observes them.


Department of Defense; Virginia; Gelman's AI; home node; HSWT 780022 3; Internet; Invisigoth; Kill Switch (AI); Ninjitsu Princess; Nebraska; The Lone Gunman

Memorable Quotes[]

BYERS: Ai -yi -yi

FROHIKE: It can't be ... it is.

LANGLY: Esther Nairn. You programmed the autonomous bots in Ninjitsu Princess, the most gnarliest piece of entertainment software ever.

ESTHER: Are these the brain donors that nearly got us incinerated?

MULDER: Don't let their looks fool you.

SCULLY: Your name is Esther Nairn?

FROHIKE: She is so hot.

ESTHER: Are you going to take off the cuffs, or do I have to do this with my tongue?

MULDER: You don't want to take a vote.

Background Information[]


  • The number of the container that is destroyed by the satellite weapons platform is HSWT 780022 3. Contrary to the standard identification system, the owner code doesn't end with a "U". Also, the last check digit is 3, instead of the correct 2.
  • This episode was written by famous science fiction author and cyberpunk pioneer William Gibson and covers themes common to his work (artificial intelligence, simulated reality, etc.) and is also the writer of 1995's Johnny Mnemonic starring Keanu Reeves. He and long-time writer friend Tom Maddox will return in season 7 as the writers of 'First Person Shooter'.
  • A "swoosh" sound effect used for the firing of the orbital weapons platform is a stock sound used in many other movies. For example, it is used in the film Predator as the sound of a shoulder-fired weapon used by the film's main villain, a predator alien. The sound can also be heard in the video game Doom.


  • The tasks of creating a 3D cybernetic image of Scully was commissioned to a freelance computer artist. Although the producers had some kind of wire-frame model in mind, the artist churned out a 3D model of Scully naked.
  • In early drafts of the script included a scene in which Scully sees a piece of hardware lying in the Lone Gunmen's pile of spare parts, picks it up and models it for herself in the mirror. She holds it up to the side of her nose until someone interrupts her and she guiltily tosses it back into the pile.
  • Editor Heather MacDougall won an Emmy Award for her work on this episode.
  • Peter Williams, who plays Jackson in this episode, is probably best known for his role as Apophis in the sci-fi series Stargate SG-1. He is the brother of producer/director/writer Stephen Williams, who directed 26 episodes of the 2004 TV series "Lost". (No relationship to actor Steven Williams who portrays The X-Files recurring character "Mr. X".)


  • In the scene where they bring Invisigoth back to see the Lone Gunmen, she says "Are you going to take these cuffs or do I have to do this with my tongue?". When it cuts away to her at another angle, you can see her mouth the words "with my tongue" again. They must have used a clip from another take and just muted her voice in order to use the angle.

Cast and Characters[]



Guest Starring




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