The world has entered a Cold War-esque setting in which nuclear holocaust appears imminent. In the hope of staving off an apocalyptic military confrontation between nations, an idealistic group of scientists working at United Labs plans to stage a fake Alien Invasion of Earth in an effort to unite all humanity against a perceived, common enemy. The scientists have managed to study the planetary conditions on the planet Theta. They draw lots, and physicist Dr. Allen Leighton (Robert Culp) is chosen to undergo radical surgical procedures that will transform him into a projected figure from a planet with a different atmosphere. Leighton's death is faked, and the bizarre series of transplants and modifications to his body proceed. His wife, Yvette (Geraldine Brooks), persists in not believing he is dead; she feels sympathetic pain as Allen suffers on the operating table. Complications arise when the effects of Leighton's transformation extend beyond his physical appearance and begin to affect his mind, a situation compounded by the scientist's strong psychic link to his pregnant wife.
The scientists' plan is for Dr. Leighton, as the Thetan creature equipped with an energy weapon and spaceship, to land at the United Nations in an effort to create initial panic. This panic, in theory, will be resolved as the world unites to fight the invader. Leighton, now a perfect simulation of an inhabitant of the planet Theta, is launched into orbit as a weather satellite but the mission goes awry when the spaceship comes down off course and lands in a wooded area near the United Labs facility. After disintegrating their station wagon with his laser pistol, Allen is severely wounded by three duck hunters armed with shotguns as he emerges from the underbrush. In a futile attempt to possibly heal his wounds, Allen stumbles back to the lab. Yvette again feels his pain and hurries to the lab looking for her husband. She arrives as the Thetan enters and collapses to the floor. Before dying of mortal wounds, the creature demonstrates "the mark against evil", a personal gesture - touching a finger to the lips, and then to the forehead - which they once shared, and Yvette then realizes the horrifying truth that the alien is, in fact, her husband.
The Architects of Tropes:
- An Aesop: Aside from the more outlandish moral (see Space Whale Aesop), the narrator makes a point that it's not fear that bring people together, but love, trust and making the effort to prosper with one another.
- Bare Your Midriff: The Thetan's costume.
- Body Horror: Allen's transformation does not look pleasant.
- Does Not Like Shoes: The Thetan's minimal outfit doesn't include footwear.
- Downer Ending: See Shoot the Shaggy Dog below for details.
- Foreshadowing: An In-Universe example for Allen's wife. His speech about scarecrows seems like small talk to her. It should've been her first clue of what Allen and his colleagues were planning. When she later learns the truth, she gets a sobering In-Universe revelation about what he was trying to tell her.A scarecrow would change everything...
- Genghis Gambit: The plot of the episode, where Allen volunteers to be turned into a fake alien to be launched at the United Nations as a scarecrow tactic. The plan blows up in their face before it can even be executed, thanks to a weather satellite (used as the Thetan's "spaceship") malfunctioning and crashing near their lab, and a nearby duck hunter killing Allen.
- The Grotesque: The Thetan is meant to look terrifying. It does.
- Ironic Echo / Meaningful Echo: The Mark against Evil. On one hand, it's ironic when Allen recieves it from his wife, because he's already started to undergo the procedure to become a Thetan, meaning he's already been touched by "evil". On the other hand, it's meaningful when Thetan-Allen gives it to his wife, because it's how he lets her know who he is. And given she'll end up a single mother because of his death, he's making sure she and their unborn child will be protected.
- No Antagonist: Every character in this story has good intentions—which is one of the reasons why it's so tragic.
- Off Screen Villain Dark Matter: It's not too hard to accept that the scientists could acquire a weather satellite or even warp Allen's biology so horribly, but where would they have gotten the know-how or resources to build a fully functional disintegration pistol?
- One-Hit Kill: The Thetan may look intimidating, but one gunshot wound is all it takes to put it out of commission.
- "The Reason You Suck" Speech: At the end, when the scientists try to explain themselves to Yvette, she gives them a brief but effective response.Yvette: I know what you thought. He told me what you thought. But how could you think?!
- Scarecrow Solution: Essentially what the scientists aim to achieve using the Thetan's DNA. Allen even uses the allegory of a 'scarecrow' to hint to his wife what he hopes to achieve. Her views are more dubious, as she aptly points out "Some scarecrows don't even scare crows."
- Shoot the Shaggy Dog: Allen's sacrifice achieves nothing and leaves his wife to raise their child alone.
- Shout-Out: Alan Moore references this episode in Watchmen to acknowledge the similarities of their Genghis Gambit plots.
- Space Whale Aesop:
- You shouldn't try to fake an alien invasion to stop the Cold War because the ship might crash.
- If you're going to do it anyway, maybe you should take the young guy with the pregnant wife out of consideration because he has so much to lose. Besides, his wife might figure out what's going on, with or without a psychic link to her husband.
- Stock Footage: Used in the film the scientists watch at the beginning, which shows a simulated nuclear attack.
- Tragic Hero: Allen.
- Was Once a Man: The Thetan Allen has become by the end.
- The X of Y: The title.