Stan Harbinger (Joe Pantoliano) is a top-rated talk show host with a flair for the outrageous and a reputation as a skeptic's skeptic. Assisted by his producer Trudy (Cynthia Nixon), Stan takes delight in shooting down callers who claim to have alien encounters, especially people like Eldon DeVries (Alan Zinyk) who believes that his body has been taken over by aliens. When Eldon commits suicide by setting himself on fire in front of Stan, Stan sees a glowing orange being leave Eldon's body but refuses to believe what he saw. A plan to syndicate the show is threatened by protests from UFO believers, angry at Stan's role in Eldon's death. Stan's skepticism is challenged when he notices that other people have the same distinctive triple heartbeat he heard coming from Eldon just before he died, and sees a woman possessed by an alien identical to the one that inhabited Eldon. Close to the edge, Stan finally loses it after Darcy Kipling (Leslie Hope), a woman he picked up in a bar, turns out to be a believer and sets him up by recording his drunken confession that he saw an alien at the bar where the two had met. He assaults Darcy's fellow believer, Moses Saxon (Alex Diakun), and is consequently fired by the station. Stan, in denial, then decides that Eldon faked his death and goes to Eldon's home to get proof, only to discover that Eldon's widow is inhabited by an alien as well. After seeing the alien use a communication device that connects to a space ship, Stan informs Darcy and Moses, desperate to get their help in publicizing the existence of aliens; the two explain that by getting himself fired he had rendered himself useless to their struggle. Stan then goes to the radio station and takes his former producer and another talk show host hostage. Stan agrees to release one hostage, Trudy, in exchange for five minutes of airtime to make his case, but the police ensure (without Stan's knowledge) that the broadcast can't be heard. Stan then discovers that he himself is inhabited by an alien, and that the two police detectives who were negotiating with him are also alien hosts. The detectives shoot and kill Stan's remaining hostage, shoot and kill Stan, and complain that they must find a new skeptic to discredit those who can see aliens.