Fox Mulder and
Dana Scully are called in to investigate a number of kidnappings in Delta Glen,
Wisconsin, where local teenagers have been found half-naked and drugged with either the phrase "He is one" or "She is one" written on their backs. Interviewing a kidnap victim, the agents initially suspect a nearby
cult, the Church of the Red Museum, founded by
vegetarian named Richard Odin. Mulder, Scully and the local sheriff, Mazeroski, attend a ceremony of the cult, causing Mulder to believe that members of the cult are
walk-ins, people whose souls have been taken over by a spirit. After an altercation between the agents and four teenagers, including the Sheriff's son Rick and Rick's girlfriend Katie, Katie is kidnapped and found the next morning. On examination, her blood is found to contain an unknown
alkaloid substance and high levels of
scopolamine. Mulder and Scully conclude that only medical personnel would have access to scopolamine, leading them to increasingly suspect Odin, a former doctor. The agents bring Odin in for questioning but are interrupted by a confrontation outside, in which a large group of Red Museum members has blocked access to the local
BBQ restaurant. An old man in a truck leads the agents to two men injecting growth hormone into cattle. The old man believes the tainted beef is making the locals more violent and aggressive. That night, Jerrold Larson, the local doctor, is killed in a plane crash. An investigation turns up evidence that trace back to the kidnapped teens, implicating Larson. Meanwhile, one of the men injecting the cows is murdered by the
Crew Cut Man. Mulder and Scully visit Beth, the mother of a kidnapped victim who reveals that Larson was giving her child "vitamin shots." Mulder notices light coming from the bathroom mirror and discovers a hidden room full of
videotapes and a camera. After being abducted from his car, Rick is found dead in a similar fashion as the other kidnapped teens, except with a bullet wound; the Crew Cut Man is seen leaving the area. The agents investigate another resident, Gerd Thomas, on suspicion of Rick's murder and the hidden room. During questioning, Gerd tells Mulder that Larson had been paying him to inoculate the cows with the same "vitamin shots" injected into the children. Convinced that they were turning into monsters, Gerd kidnapped the children and drugged them with scopolamine and
psychedelics to make them "pure" again. During the interrogation, Scully recalls and recognizes the Crew Cut Man as the assassin who
killed Deep Throat. A toxicology report reveals the presence of a mysterious substance known as "Purity Control", leading Mulder to theorize that Larson had been injecting the children with alien
DNA. He convinces Mazeroski to round up all of the families of Larson's patients, believing their lives to be in danger, and have them hidden at the Church of the Red Museum. Mulder tracks down the Crew Cut Man at a beef processing plant that has been doused with gasoline. The Crew Cut Man locks Mulder in a freezer and lights a match. Scully, Mazeroski and his deputies arrive, interrupting the Crew Cut Man's attempts to destroy the plant. Mazeroski kills the Crew Cut Man in revenge for Rick's murder, to Mulder's dismay. Scully reports that the Crew Cut Man had no records on file with the
FBI or other agencies. The material injected into the cows and children is found to be an unknown substance. All the children who were inoculated came down with a
flu-like illness, but those in the Church of the Red Museum, being vegetarians, did not become ill. Scully thinks the Church of the Red Museum may have been used as a
control group without their knowledge and declares the case open and unsolved. ==Production==