On Christmas Eve, Mulder and Scully find themselves trapped in a haunted house with two ghosts who are determined to prove just how lonely the holiday can be.
On Christmas Eve, Mulder and Scully stakeout a house that is supposedly haunted by the ghosts of two lovers who killed each other in a lovers' pact 81 years before. Inside, the agents find two apparitions who are more than willing to give insight into the relationship and personalities of Mulder and Scully.
- On Christmas Eve, Mulder calls Scully out to take a look at a haunted house. They get locked in.
A piano starts to play. Scully sees a ghost. They venture up the stairs, Scully arguing against the existence of ghosts the whole way. At the top of the stairs, the doors are all locked until one opens by itself. They enter into the room, which opens out over a large, brightly lit hall, with a fire that has just gone out in the fireplace. Mulder explains that the last three occupants of the house have all met tragic ends on Christmas Eve. A heartbeat appears to come from the floor; Mulder pulls back a rug to look for it. Under the floorboards he finds two bodies, apparently shot to death. They are wearing identical clothes to Mulder and Scully. Panicked, they run for the door, but find that it leads back into the same room. Mulder tests the theory by leaving the room again, but does not reappear, and they become separated.
Trying to find Scully, Mulder wanders around until he meets an older man. Mulder accuses him of being a ghost. The man says Mulder is the first one he's seen come armed, but the hole in the floor and the corpses have disappeared. He says he is a mental health therapist, and calls Mulder an egomaniac and much other psychobabble. He tells Mulder that he can change his life. Mulder tries to follow him through a door but bumps into a brick wall.
Scully, also wandering around, meets an old lady in a nightgown. Panicked, she points a gun at her, then apologizes and tries to show her the bodies, which have again disappeared, and the doors are bricked up. She also speaks psychobabble to Scully. The man comes in through the bricked up wall, and Scully holds them both at gunpoint. She finds they both have holes in their bodies, and faints. The two, who are ghosts, then discuss their success or failure at luring people to their deaths each year.
Mulder attempts to climb out of the room, but is confronted by the woman. He identifies them as Lyda and Maurice, and she finds a book called "The Ghosts Who Stole Christmas" and identifies themselves as the couple in a story.
She explains that she was involved in a murder-suicide, and says that Scully is going to shoot him as well. She suggests that Mulder shoot her first, so they will be able to be together forever.
Scully wakes up, but is still stuck in the room. Maurice tells her he's locked the doors, and that Mulder has set all this up so he wouldn't be alone at Christmas. She pulls a gun on him and orders him to open the door, where Mulder has been outside knocking. He opens the door, Mulder walks in and shoots at Scully. He says it is either him or her. He's apparently bought into the ghosts' stories of loneliness, and shoots her in the stomach. Scully collapses, but Maurice grabs Mulder before he can shoot himself. It is revealed that Mulder was actually Lyda.
Mulder then walks into a room, and finds the dying Scully on the floor. She shoot him, but this time Scully was being played by Lyda.
Near death, the two crawl toward each other, still holding guns on each other. Then Mulder realizes that the shootings were all in their heads, and they stand up and walk out of the house, as "Have Yourself A Merry Little Christmas" plays on a record player.
Maurice and Lyda relax in front of a fire the next morning, and reminisce about how they almost got Mulder and Scully.
Mulder watches Alistair Sim playing Scrooge when someone knocks on the door. It is Scully. She asks if any of it really happened. They wonder if the ghosts' psychobabble has any truth in it, and exchange gifts.