Agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) are called in to investigate a number of kidnappings in which children are recovered half-naked and drugged, with either the phrase "He is one" or "She is one" written on their backs. Meeting with Sherrif Mazeroski, the agents initially suspect a nearby cult, the Church of the Red Museum, which was founded by vegetarian Richard Odin. Mulder, Scully and Mazeroski attend a ceremony of the Red Museum, causing Mulder to believe that they are walk-ins, people whose souls have been taken over by someone else. One of the kidnap victims claims to have felt an animal spirit enter him. The girlfriend of the sheriff's son is the latest to be kidnapped and found, and material in her blood appears related to Odin, who was evicted from the American Medical Association back in 1986. Mulder and Scully question him, then meet an old man who shows a pair of men injecting growth serum into cows. That night, the local doctor, Jerrold Larson is killed in a plane crash. Investigating the remains of the crash turns up shipping orders that trace back to the kidnapped teenagers. One of the men injecting the cows is murdered by the Crew Cut Man (last seen in The Erlenmeyer Flask). The other, a peeping Tom named Gerd Thomas is revealed to be the kidnapper when the agents find a hidden supply of video tapes in the home of one of the kidnap victims. Thomas claims that Dr. Larson had been turning the children into monsters due to the drugs he had been injecting in them. Meanwhile, the sheriff's son turns up murdered by the Crew Cut Man. Having passed by him on the road, Scully recognizes him as the assassin who killed Deep Throat and tells Mulder. Mulder believes that Dr. Larson had been injecting the children with alien DNA. Mulder convinces the sheriff to round up all of the children who had been receiving treatment from Dr. Larson and hides them with the Church of the Red Museum. Mulder tracks the Crew Cut Man down at a beef processing plant where is he is about to burn down the place. While Mulder wants him alive, the angry sheriff kills him as revenge for the murder of his son. Scully reports that the Crew Cut Man has no records on file with the FBI or the National System of Records. The material inoculated into the cows and children is found to be an unknown substance. All the children who were inoculated come down with a flu-like illness while those in the Church of the Red Museum are don't, causing her to think they were a control group