A hitchhiker in Utah desert is picked up by a bus full of people, then watches in horror as the bus stops and a disabled man is stoned to death by the other riders. Scully heads to to investigate, as his spine was found in an advanced state of deterioration. She is curious when the same bus passes her on the road, but ends up stranded in a remote community when a gas station attendant gives her watery fuel. When the phones don't work either, she suspects that the residents are trying to keep her from leaving.
Scully stays overnight, and is called to help the hitchhiker, who is also in the community and suffering a seizure. She finds a bloody hole in his back and wants to get him to a hospital, but finds that no one has a car. Doggett gets concerned when he finds that Scully hasn't checked in with the sheriff's office and begins to track her down. Worried that she's in a cult compound, Scully tries to help the hitchhiker as best she can; she also retrieves a tail-like thing from his back after seeing something moving under the skin. Figuring that a parasitic organism has taken up residence on the hitchhiker's spine, she plots to get him out of the community. She also gives him her gun, which is unfortunate since he's apparently joined the cult's side.
As Scully discovers the bus, the cult members converge on her; the hitchhiker, now disabled, allows himself to be murdered as the cult removes a giant worm-like creature and plants it in Scully. Doggett finds Scully imprisoned and begins to hotwire the bus to get her out. As the parasite worms its way toward her brain, Scully begs Doggett to cut it out of her neck. He does so and shoots it dead, much to the dismay of the cult members. A week later, Scully has recovered and the cult members are being brought up on charges and claiming religious persecution based on their desire to worship a horrible parasite as the Second Coming. Scully apologizes for leaving Doggett off the case and promises not to do it again.
Lawrence Pressman, who plays Mr. Milsap, also played Dr. Benjamin Canfield on Doogie Howser, M.D.
Episode Body Count
Disabled man: beaten to death by cult members, Scully says he is also found to have "the spine of a 90-year-old woman."
John Doe: Scully asks Doggett to look into a case where a strange mucus was found on a body in 1991.
Three other cases: Doggett finds that there were three other unsolved cases in recent years where victims were found in the desert with their brains missing.
Hank Gulatarski: stoned by a cult member after deciding to transfer the parasite to Scully.
The Holy Parasite: shot by Doggett after he pulls it away from Scully's spine.
Cumulative Body Count (165/202 episodes, 1/2 movies)
Humans: 1,743Creatures: 116
Grand Total: 1,922