|Original Airdate:||February 13, 2000|
|Written by:||Chris Carter & Frank Spotnitz|
|Directed by:||Kim Manners|
After years of believing that his sister was abducted by aliens, Mulder finally learns the long sought-after answers to her true fate with the help of a psychic.
FBI Special Agents Fox Mulder and Dana Scully aid the Sacramento Police Department in an investigation of a brutal murder committed by Ed Truelove, the owner of Santa's North Pole Village. As more child bodies are discovered, he admits to having killed twenty-four different children but denies that he played any part in the death of Amber Lynn LaPierre. Mulder is approached by Harold Piller, a self-professed psychic who tells Mulder that he has helped police forces all over the world and has proved, on various cases, that children's bodies have been taken by walk-ins. Piller has come to the conclusion that the walk-ins save children who suffer terrible fates.
Scully meanwhile worries about Piller's influence on Mulder. The two FBI agents later return to Washington, D.C., where Mulder keeps searching for evidence. Back in California, Piller experiences another vision of Samantha Mulder, which leads the three investigators to April Air Force Base. Scully finds evidence regarding Samantha's disappearance, linking this incident to the Cigarette Smoking Man. When she returns to her apartment, Scully finds the Cigarette Smoking Man, waiting for her. He tells her that he originally called off the search for Mulder's sister because he knew she was dead. Meanwhile, Mulder breaks into April Air Force Base, where he uncovers evidence that Samantha lived with the Cigarette Smoking Man along with his son, Jeffrey Spender. Scully finds a police report matching the description of Samantha in 1979; the investigators find out that she was taken to a hospital emergency room.
They trace the nurse who treated her and the nurse, Arbutus Ray, claims that Samantha disappeared in the same way that Amber did – without a trace. Mulder later on walks through a forest near Ray's home, and receives a vision of Samantha that influences him to realize that his sister is in a better place, a realization that at last enables him to feel free.
- The X-Files' crew had built two permanent stages, when shooting Season 7 of the television series; these stages were five and six at 20th Century Fox. The crew also used stage eight as their "swing set". The first scene of this episode was shot in Griffith Park, above the playground for children. The first scene with the walk-ins rising up from their grave was a "tricky" scene, according to director Kim Manners. To get the kids into the graves, the crew told the children that the graves were actually forts, saying that the kids would not collaborate if they told them to lay themselves in a grave. ("Closure" audio commentary)
- The scene at April Air Force Base was shot in San Bernadino, California, at a closed airfield. Close to the airbase, there was a huge abandoned house complex, built and used by the United States military. This air force base was renamed April Air Force Base, since the producers could not use the name March Air Force Base. One of the shots set inside April Air Force Base was filmed at a sound-stage in Los Angeles. The scene at the restaurant was shot in a location on Sepulveda Boulevard, at a hotel that had been standing there for thirty to forty years. ("Closure" audio commentary)
- "My Weakness", a song by Moby from his album Play, is used in this episode, during the first scene (in which the FBI discover a mass grave site containing the bodies of dozens of missing children), and near the end (when Mulder apparently encounters his sister's spirit). Chris Carter never told the series' resident composer, Mark Snow, about this change, although Snow has since said that his reaction to the use of this composition was more positive than negative, adding that it was a "perfect" fit for the scenes in which it can be heard. 
- Anthony Heald as Harold Piller
- Stanley Anderson as Agent Lewis Schoniger
- Rebecca Toolan as Teena Mulder
- Patience Cleveland as Arbutus Ray
- Christopher Wynne as Base Officer
- Ed Beechner as Deputy
- Megan Corletto as Amber Lynn LaPierre
- Nicholas Stratton as Ghostly Boy
- Mimi Paley as Young Samantha Mulder
- Fort Atkinson as Detective #1
- Jeff Xander as Detective #2
- Norman Smith as Detective #3
SEMICOLON-SEPARATED LIST OF ITEMS/LOCATIONS REFERENCED IN EPISODE (BUT NOT LINKED TO IF ALREADY LINKED IN SUMMARY OR GUEST STARS SECTIONS)