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''Impostor'' is a 2001 science-fiction film, based on a short story by Creator/PhilipKDick. It starred GarySinise, Vincent D'Onofrio, Madeleine Stowe, and Mekhi Phifer.

In the middle of the 21st century, humanity was attacked by an alien civilization from the Alpha Centauri system. The Centauri have bombed Earth continually for over 45 years, reducing large parts of the Earth to wasteland and destroying effective goverment in others. A global totalitarian government takes control and the major cities are fitted with defensive shields to protect the last vestiges of civilization. The Centauri resort to more covert means to destroy humanity, using biorobots armed with atomic bombs to infiltrate the cities and kill key political figures.

Dr. Spencer Olham (Gary Sinise) is a renowned scientist working on government weapons projects. One day he is unexpectedly arrested and accused by Major Hathaway (Vincent D'Onofrio) of the Earth Security Administration of being a robot sent to assassinate the Chancellor during an upcoming meeting. Olham goes on the run and heads to the outer regions to prove his innocence.

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!!This film provides examples of:

* AliensAreBastards: The Alpha Centauri aliens attacked humanity and try to destroy Earth civilization for no apparent reason, as their motives aren't revealed in the film.
* ArtificialHuman: The Centauri can create manufactured humans with an atom bomb built into them which will explode if they're exposed to an appropriate trigger.
* BittersweetEnding: [[spoiler:The hero and his wife are dead and one of their roboclones explodes. Hundreds of acres of forest are destroyed, killing thousands of people and Major Hathaway, who had been trying to prevent exactly that from happening the entire film. The assassination of the Chancellor has been prevented however and Cale gets his sister the medicines that Spencer provided him with.]]
* DeathByAdaptation: [[spoiler: In a type B example, Nelson survived up to the end of the end of the story and was the one to prove that Olham was in fact a bio-bomb, then died along with everyone else in the explosion. In the film, he's accidentally killed by Olham halfway through.]]
* DiabolusExMachina: [[spoiler:The film revolves around a man trying to prove that he's not an alien-created replicant of himself with a bomb in his chest. At the climax of the movie, the man and his wife find the alien crash site where he was allegedly killed, and discovers his wife's body inside the spaceship, proving that his wife was the replicant instead. Then suddenly, in the last few minutes, the authorities that were chasing him through the whole movie discover the man's body as well, proving that he was also a replicant, and the man promptly explodes and kills everyone in the area.]]
* DomedHometown: The cities are covered by defensive shields to protect them from Alpha Centauri attacks.
* {{Fanservice}}: The somewhat long interrogation scene in which Gary Sinise is shirtless the whole time.
* InspectorJavert: Dr. Spencer Olham is being chased by an officer who's convinced he's an alien biorobot who killed the original and took on his personality in order to detonate a bomb and kill the Chancellor. He plans to prove that by vivisecting the protagonist and disarming the explosive. The protagonist spends the whole film trying to prove he's human. [[spoiler:The officer turns out to be right]].
* KillAndReplace: Dr. Spencer Olham is accused of being an alien biorobot who has killed and replaced the scientist. They plan to prove themselves right by cutting him open to look for a biological bomb. He escapes and spends the rest of the movie trying to prove them wrong. [[spoiler:They're right. Both he and his wife have been killed and replaced with the dopplegangers taking on the originals' memories. When he finds out the truth, the bomb in his chest explodes]].
* NotHisSled: Played with. [[spoiler: In the original story, only Olham is a fake. In the film, his wife turns out to be the fake instead, thus proving that Olham is human. Then it turns out the real Olham really was killed and he is a living bomb.]]
* ReplicantSnatching: The premise is that look-alike copies of key people can be sent after targets, exploding violently once contact is made. The hero is accused of being one such impostor.
* ShootTheShaggyDog: [[spoiler:It ends this way in literally the last few minutes of the movie, with the main character spending the movie on the run and trying to prove that he's not an alien-created replicant bomb. Except that it turns out he ''is'', at which point he promptly explodes and takes every surviving character in the movie with him, save two characters who weren't anywhere near the explosion.]]
* TheReveal: [[spoiler:Two in succesion. Dr. Olhamís innocence is proven when Hathaway reveals that his wife has been replaced with the real biorobot sent to assassinate the chancellor. Shortly afterwards they discover the real Olhamís body, as it turns out that both the Olhams had been killed and replaced with copies.]]
* TomatoInTheMirror: [[spoiler:Dr. Olham is, in fact, the robo-bomb he's been trying to prove he ''isn't'' for the entire movie. His wife is one, too.]]
* WhyAmITicking: This is the basis for the plot of the movie. The main character of the story is suddenly arrested and told that he's not the man he believes himself to be: he's really an ArtificialHuman that is designed to be indistinguishable from the original except that, when he encounters the proper "trigger", he will explode. He doesn't believe it, escapes from his would-be executioners, and tries to find evidence to prove that he isn't an impostor. [[spoiler: At the end of the movie, he discovers that he really is an impostor, and then promptly explodes.]]

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