On Christmas Eve, Mulder is staking out a haunted house in Maryland where two people named Maurice and Lydia killed each other in 1917 in a lovers' pact. He's also invited Scully along, and though she has better places to be she ends up accompanying him into the house after Mulder nabs her car keys. Scully thinks someone might just be living there when they find the lights on and a smoldering fire. Mulder says three double murders have happened in the house since 1917, and they're pretty freaked out to find two corpses resembling themselves under the floorboards.
The agents try to leave, but find that they just keep going through the same room. When they try going through different doors, they end up getting separated by a bricked-off passage. Mulder meets Maurice, who says it's his house and gives Mulder a bit of a talking to about mental health before convincing him (falsely) that there's no wall. Scully, meanwhile, finds Lydia, who also does a similar psychological rundown on Scully. Maurice enters, and Scully faints after seeing them both with gaping bullet wounds.
Maurice and Lydia are apparently using the psychological/bullet wound approach to try to boost their double murder count after the house was condemned. Mulder meets Lydia and immediately recognizes her as a ghost, though he is surprised that they've aged. Maurice visits Scully, and hears Mulder calling to her. The agents are reunited, and Mulder, saying they're simply exacerbating their loneliness, shoots Scully and prepares to kill himself. The shot changes to show that it is apparently Lydia that has done this, and Scully shoots Mulder as he goes to her...an act apparently committed by Maurice.
Mulder and Scully drag themselves on trails of blood toward the door...Christmas cheer, eh? Mulder realizes that neither has actually been wounded, and they make it out of the house to find themselves uninjured. Maurice and Lydia are a little bummed at letting them escape, but glad to be together. Scully visits Mulder on Christmas Day, and they exchange gifts as the snow falls. Aw...
Both ghosts are well known. Ed Asner, as Maurice, most recently voiced Carl Fredricksen in Up, and played Lou Grant in The Mary Tyler Moore Show and a successful spinoff focusing on the character. Lily Tomlin, as Lydia, also played Deborah Fiderer in The West Wing, Kay Carter-Shepley in Murphy Brown, and voiced Ms. Frizzle in The Magic School Bus.
Episode Body Count
Maurice and Lydia: killed each other in a lovers' pact in 1917.
Six tragic couples: Mulder says three double murders have occurred in the house in the past 80 years.
Cumulative Body Count (123/202 episodes, 1/2 movies)
Humans: 1,447Creatures: 99
Grand Total: 1,607