“Demons” is episode twenty-three of season four of The X-Files.
Mulder is being told to wake up by his sister, Samantha. When he does, he glances in the mirror and sees his younger self. His father and mother are arguing about something.
Then, he properly wakes on the floor of a motel room. He collapses onto the bed and there’s blood on his shirt, which he notices.
Scully is in bed when Mulder wakes her. She asks him what time it is; he doesn’t know. Is something wrong? He thinks so. Where is he? Mulder thinks he’s in a motel room in Providence, Rhode Island. What’s he doing there? He doesn’t know, but he has blood all over him. He doesn’t think he’s hurt; he doesn’t think it’s his blood.
When Scully arrives, Mulder is in the shower, shivering. He can’t get warm and she says he’s in shock. She asks him questions and Mulder says he woke on the floor with a pounding headache. He thinks he was alone, but doesn’t know as he doesn’t remember anything. Not even what day it is. It’s Sunday. The last thing Mulder remembers is talking to Scully on the phone in his apartment. That was on Friday. Scully says Mulder packed a bag with a change of clothes. He didn’t take anything and he’s sure he didn’t cut himself. Scully asks where Mulder’s weapon is. He doesn’t know. It’s in his bag and two rounds have been fired. Scully wants Mulder to go to hospital, but he wants to know what happened. She’s concerned that something bad could happen. Mulder finds some keys’ no, they aren’t Scully’s. It says ‘AMY’ on the keyring.
According to the manager, Mulder checked in alone and didn’t call or see anyone. He drove and the license of the car is registered. Scully finds it’ there’s blood on the wheel. It’s not Mulder’s car, but the keys open them. The car is registered to a David Cassandra. Elsewhere, a man is cutting faces from photos. His face. Blood trickles down from his scalp.
They head to the Cassandras’ house, but the housekeeper says they aren’t there. Mulder sees a painting of a house and asks about it. Amy painted it but Mulder recognises it. He thinks he’s seen it before. It’s the house Amy grew up in and has special meaning. It’s all she paints and she’s done many, many paintings. Well, that’s a bit creepy. The housekeeper gives the location and Mulder knows it; his parents had a summerhouse here when he was a kid.
When they get to the house, it looks abandoned and Mulder is stricken by a headache. He gets a flashback of the argument again, and this time sees a young CSM. When he comes to, Mulder tells Scully he feels really good. Scully disagrees. The keys open the house and, inside, the Cassandras are there. Both dead; both shot.
The police are called and the detective questions Mulder about what he saw. He clearly isn’t convinced by Mulder’s statement that he doesn’t remember anything. Scully wants Mulder to head to the hospital and the detective wants Mulder to ride with them there. Scully wants to look at the bodies. When looking at them with the ME, she sees a puncture wound to the head and wants it examined. Yes, it’s obvious what killed them; her interest is why they died.
The detective enters an interrogation room with a paper bag asks Mulder if he wants to change his story, because he has evidence that contradicts it. He’d like to believe Mulder’s memory lapse is real and that he murdered the Cassandras in a fit of insanity. Mulder’s gun seems to be the murder weapon, the blood on his shirt belongs to the Cassandras. He arrests Mulder on suspicion of murder. Scully finds the whole thing very suspicious.
Mulder has more flashbacks to his past and wants to find out more about what happened back then.