Leyla Harrison, an FBI agent with a passion for the X-Files that Mulder and Scully investigated, alerts Scully, Doggett and Reyes to a case she believes is an X-File involving a young boy with an overactive imagination.
This episode starts in a children's bedroom in Fairhope, Pennsylvania, where a little boy lies awake in the dark as he hears scratching noises on the window. Frightened he tries to take a look underneath his bed. He calls his father who takes a glimpse if there is anything under the bed and despite having seen a shadow, he tells his son that everything was alright and leaves the room again. As the boy tries to fall asleep again, he sees something underneath the bed and tries to get out of the room calling for his father screaming "They are in here!" but the father is seen outside the door, keeping it closed to keep his son inside.
Scully's trying to have her lunch at the FBI headquarter as Leyla Harrison visits and shows a picture of a dead woman which she claims to be an X-File. She tells the story of a boy called Tommy who says that a monster called his mother and his cat as well, showing Scully a passport picture of Tommy, the boy from the teaser. Scully doesn't think it's an X-File and rejects Harrison, telling her that she believes that it was a suicide where the woman stabbed herself 16 times with a knife.
At home, Scully gets a call from Monica Reyes who's on the road to Pennsylvania with Doggett and Harrison trying to tell her about the case, only to find out that Leyla Harrison already told Scully about it but didn't inform Reyes about it. Despite Scully's opinion, Harrison convinces the two agents to drive to Fairhope.
Mr. Collinson, the father from the teaser in seen, trying to bury something in his garden as the agents and Harrison arrive around seven o' clock in the evening.
They wish to speak to Tommy but the father tries to send them away telling them his son was sleeping. Tommy appears at the door because he heard noise outside but when they try to find out what he knows, when Harrison asks him about the monsters he replies rather unconvincingly that monsters don't exist. Reyes, Doggett and Harrison start to leave again, being watched by Tommy and Mr. Collins, Tommy telling his father the monsters won't let them get away. As Doggett starts the motor, blood splashes against the window. They open the car and find out that something was inside the car that broke the engine.
Scully gets a visit late at night by a boy that brings her the dead cat that Harrison talked earlier about.
In the Collins' house Doggett tells Reyes and Harrison that the motor can't be fixed that quickly as they hear the boy screaming. They find his dad keeping the door closed, but push him away and see insect-like creatures crawling on the floor. Doggett tries to shoot them, but even when they get shot, they revive and escape. Later the boy sits at a table and draws. Doggett tells Reyes that he couldn't find any creatures in the room. They ask Tommy about it who explains that those are the things that killed his mother but his dad said he wasn't allowed to talk about it. Mr. Collinson tells them that everything was in control, but that "they" have arrived and want to kill everyone. He claims that "they" cannot be killed and when you try to one becomes two.In the meantime Scully cuts open the cat, accompanied by the young man who brought it to her apartment as the telephone rings and the sheriff of Fairhope, Doug Huben, calls. Scully wants him to find the other agents.
In the Collinson's garden Doggett tries to dig out whatever Mr. Collinson is trying to hide in his garden. He finds the broken mirror from Tommy's room. As they want to leave the house and go to the sheriff's office the sheriff appears in the apartment. Mr. Collisons claims that it's not the sheriff, who attacked Doggett. As Doggett hits him with his fist, his hand goes right through his stomach.
Scully thinks that the cat as well as Tommy's mother had something inside that was painful and they tried to cut it out.Doggett and Reyes have problems finding out what is going on in this house because nothing makes sense and there is no connection, talking about an earlier X-File Scully and Mulder have been involved in, being caught in a toxic mushroom that created hallucinations. They confront Tommy's father who only lets them know that the creatures won't hurt Tommy, as Reyes looks at some drawings Tommy made including drawings of the scorpion-like monsters and a picture of Reyes with a monster inside. When she want to know why he draws things like that he answers "Because I'm afraid".
Scully arrives at the real sheriff's office trying to find a way to the house but since it is snowing, he tells them that there's ice on the streets.Reyes comes down into the living room, aching from pain in her stomach telling the agents that the boy is behind this. Something's moving in her stomach. Doggett wants to stop the boy from doing it. He enters his room but falls down a dark hole, being attacked by the creatures but soon stands up; he and his surroundings are perfectly normal. Harrison tries to help Reyes but her eyes start bleeding. The boy is seen drawing a picture of Harrison with bleeding eyes. Doggett returns and explains to Mr. Collins that none of this is really happening, that those are just illusions. He brings the others except Tommy to the car, returns to the house and after emptying a jerry can onto the floor, sets the room on fire with a tossed match. Rather then watch the flames however, Doggett is seen carefully observing Tommy. Tommy is scared and passes out, and the hallucinations stop. Later on, Reyes returns to the house and finds out that Doggett spilled only water on the floor, making the boy believe that he would set the house on fire.
Back in the FBI headquarters, Harrison tells Doggett that he did a very good job, better than Mulder could have ever done it. Doggett's inability to believe in the illusions he was seeing protected him, making him the best agent for the case.
Tommy is seen in the last scene, lying in a hospital in front of a dozen televisions, each with a different channel with the voice comment from Doggett saying that they try to reduce the boy's fantasy. The scene is very similar to one in the movie "The Man Who Fell to Earth" starring David Bowie.
- This episode shares its name with an album by David Bowie entitled Scary Monsters (and Super Creeps).
- Here, Agent Harrison references the Season 3 episode, "D.P.O.", remembering that "a teenager was struck by lightning - his body affected the electrical workings of everything around him" and that "Agent Mulder wasted no time closing that case".
- Doggett later references an episode of the Mulder and Scully era himself - "Field Trip" from Season 6. He apologises for sounding like Agent Harrison and remembers that Mulder and Scully "were trapped underground with these mushroom spores that caused hallucinations".
- In this episode, Tommy utters the famous phrase, "I made this" while he shows a drawing he made to Reyes. This is also the phrase spoken while the TenThirteen logo appears after the end credits of every X-Files episode.
- Gillian Anderson as Special Agent Dana Scully
- Robert Patrick as Special Agent John Doggett
- Annabeth Gish as Special Agent Monica Reyes
- Jolie Jenkins as Special Agent Leyla Harrison
- Brian Poth as Gabe Rotter
- Scott Paulin as Jeffrey Conlon
- Gavin Fink as Tommy Conlon
- Steve Ryan as Sheriff Jack Coogan