S8E5 · Invocation

In 1990, Billy Underwood goes missing at a school fair in Dexter, Oklahoma. Ten years later, Billy's mother Lisa Underwood is called to the local elementary school. She learns that Billy has mysteriously re-appeared at the school, but does not seem to have aged in the decade he was missing.

Dana Scully (Gillian Anderson) and John Doggett (Robert Patrick) arrive at the police station to see Billy. Doggett interviews the boy, who seems to be mute. In an attempt to get Billy to speak, Doggett keeps his backpack from him. This infuriates Lisa and leads Scully to question Doggett’s expertise in child abduction cases. Scully suggests that Billy is an alien abductee, but Doggett believes Ronald Purnell, a local delinquent, may have been involved in the boy's disappearance. Doggett questions Purnell, who expresses confusion when the agent suggests that he should meet Billy. As Doggett sits in his car, he pulls out a school photo of a young boy.

When Billy is returned home, his brother and father are uneasy about his presence; Lisa is blind to these problems. While Lisa and her husband Doug argue about Billy, he wanders into his brother’s room holding a knife. Lisa finds a bloody knife in Josh's bed the next morning, although the boy is unscathed. Billy stands in the room staring at Josh. Forensic analysis shows the blood to be Billy's, although there are no injuries on him. The knife bears a crude star-like symbol that Billy drew while being interrogated by Doggett, a symbol that was also drawn by a psychic investigator who worked with the police following Billy's disappearance ten years earlier.

The Underwoods reluctantly agree to let Billy speak with the psychic, but when Doug attempts to drive him to the meeting, Billy seemingly disappears from inside the family minivan, only to reappear in Josh's room, frightening Josh with his silent staring. Meanwhile, at Purnell's trailer, his mother's boyfriend, Cal Jeppy, shows up and hassles him. Purnell goes into the woods and digs up a skull. Later, Jeppy blackmails Purnell into silence over something related to Billy.

Scully and Doggett bring the psychic, Sharon Pearl, to meet Billy. After touching Billy, Pearl says that she feels powerful forces acting through him, and that she senses emanations from Doggett as well, claiming he lost someone just like Billy. She then appears to suffer a seizure and the mysterious symbol forms on her forehead. As Scully and Doggett discuss Sharon's condition, Scully plays a taped recording of her utterances while having the seizure, then reverses the tape to reveal a child's voice singing a lullaby, All The Pretty Little Horses.

They notice Purnell driving up to the Underwood home and Doggett gets out to question Purnell. Purnell panics when he sees Billy inside his car, driving off when Doggett also sees the child, but after a short pursuit, Purnell is arrested and the agents fail to find Billy in the vehicle. Elsewhere in town at a gas station, Josh Underwood is lured from his father's car by a pony and horse trailer. As his abduction unfolds, the star-like symbol Billy and the psychic drew is shown to be a painted logo on the trailer for Cal's Pony Ride-Along.

After interrogation by Doggett, Purnell confesses to snatching Billy in 1990 on behalf of someone else. Doggett recognizes Purnell was also a victim, and with enough prodding, gets a name: Cal Jeppy. The police and the two FBI agents go to Jeppy’s home and find Josh in a compartment under the floor of his horse trailer. Doggett chases Jeppy into the woods, catches him, and, after catching a glimpse of Billy, discovers the skull Purnell dug up earlier where the now vanished boy was standing. As the Underwoods grieve over the shallow grave of their long-dead son, Doggett expresses incredulity that the case's conclusion was an instance of justice from beyond the grave and laments their inability to explain it. Scully, however, reasons that the body is explanation enough and that the important thing is that Josh Underwood was saved from the same fate.