S5E12 · Bad Blood

One night, Fox Mulder (David Duchovny) kills a young man whom he believes to be a vampire, but who it turns out is wearing fake fangs. Afterwards, he and his FBI partner, Special Agent Dana Scully (Gillian Anderson) must report to Assistant Director Walter Skinner (Mitch Pileggi). Before they do so, they attempt to get their stories straight.

Scully tells her version of the story in a flashback to the previous day. She arrives at work and Mulder tells her about a murder in Texas, which he believes to be the work of vampires. In her telling, Mulder is exuberant, insensitive, and irritating, while she is calm and mindful. The agents travel to the small town of Chaney, Texas, where they meet Sheriff Hartwell (Luke Wilson), whom Scully finds very charming. Mulder and Hartwell leave to investigate further while Scully autopsies the body. She discovers that the victim, whose last meal had been pizza, was incapacitated with chloral hydrate.

She returns to the motel room and orders a pizza, but Mulder soon appears and sends her back to autopsy another body. She leaves him just as her food is delivered. When she finds that the second victim had also ingested chloral hydrate in a pizza, she realizes Mulder is in danger and returns to the motel room. She finds him about to be attacked by the pizza delivery boy, Ronnie Strickland (Patrick Renna). She shoots at Ronnie, who runs off into the woods. When she catches up to him, Mulder has gotten there first and hammered a stake into Ronnie's heart.

Mulder tells Scully his version. In his recollection, he is sensitive and polite to Scully, while she is dismissive and irritable, and clearly enamored with Sheriff Hartwell (who, in Mulder's telling, is unrefined and has obvious buck teeth). While Scully is performing the autopsy, Mulder and Hartwell are called to the local RV park, where they find another exsanguinated body. Mulder returns to the motel room; after Scully has left, he eats her pizza and realizes that he has been drugged. Ronnie enters, with glowing green eyes, and prepares to attack Mulder, but Mulder manages to postpone his demise by scattering sunflower seeds on the floor, which Ronnie compulsively starts to pick up. Scully enters and shoots Ronnie, but the bullets have no effect, and Ronnie runs out with Scully in pursuit. Mulder recovers from being drugged, fashions a stake from a chair leg, and runs after Ronnie.

Back in the office, Scully says that no one will believe Mulder's story; he contends that Ronnie's autopsy will vindicate him. But when the Texas coroner preparing to perform the autopsy removes the stake from Ronnie's chest, he wakes up and escapes. Skinner sends Mulder and Scully back to Texas to investigate. Scully stakes out the cemetery with Sheriff Hartwell, while Mulder goes to the RV park. As they wait, Sheriff Hartwell gives Scully a hot drink, apologizes to her on behalf of Ronnie, and says that he makes them all look bad, making it clear that he too is a vampire. Scully belatedly realizes she has been drugged, as she sees Sheriff Hartwell's eyes turning green.

At the RV park, Mulder finds Ronnie asleep in a coffin. As he tries to arrest him, Mulder is surrounded and overwhelmed by people with glowing green eyes. He wakes up the next morning in the RV park, in his car, where he is rejoined by Scully. They are both unharmed, and the vampires have departed in their RVs. Back in Washington, the agents give their unified report to Skinner, who is dumbfounded.