A research scientist is checking out an experimental jet engine when the door of the room closes on him and the fan is started sucking him into it and killing him instantly. The man at the controls is none other than a retarded janitor named Roland.

Mulder is intrigued by this case when it turns out that he is the SECOND scientist to die after a man named Arthur Grable who also worked on the same project with them. When Mulder investigates the crime scene he finds some writing on a chalk board which does not match any of the other scientists. Mulder asks who else was here at that time of night and one of the scientists tells him that only Roland was here. He appears to be the main suspect but for the problem being he is retarded.

Mulder and Scully interview Roland where Mulder grabs one of the pieces of paper that Roland had been working on. He gets the handwriting analysed compared with the writing on the chalk board but they do not match. Meanwhile, Roland sees a strange vision in his dreams and decides to act it out by assaulting one of the other scientists, Dr. Keats and shoving his head into a tank of liquid nitrogen. He forces him to the floor as the camera moves away and we hear a heart-wrenching sound of shattering glass (But we all know what it really was!).

Again the agents visit the crime scene and see that someone had accessed Dr. Grable's and started working on his research adding even more information to it. They try to access the password but it is denied. Mulder has an idea and decides to try the numbers written on Roland's piece of paper. It works and they discover that his files had been worked on for six months before that. Scully can't believe that Roland can really be doing these complicated mathematics so they go and interview him again where he says that "I'm not supposed to talk to them". The agents research Roland's background history and come across a startling discovery, Roland and Dr. Grable are twins.

Mulder has a theory that Grable and Roland have a psychic bond when they find out that Grable's head has been cryogenically preserved. He claims that Grable is controlling Roland to murder the scientists as he wants revenge for some reason. When they interview Roland once again to try to find out more he runs away back to the lab where he traps the final scientist in the jet propulsion lab. Here we learn that all the scientists were responsible for Grable's death and that he won't be in peace until all the scientists have been murdered. Roland starts the fans and the scientist is about to be killed when Mulder and Scully rush in convincing Roland to type in the secret passcode and stop the fans.

Mulder recommends Roland's release when he is to be held for examination as we see him packing his bags and leaving....for good.