The Doctor is strolling through Maine. He stops somewhere, enjoying some fish and chips, when Stephen King comes and sits next to him.
"I have something for you. An unfinished draft of something that happened twenty years ago. Perhaps you'd like to finish it. It does involve you after all."
Now having his curiosity, the Doctor looks at the title of the draft, and his expression darkens.
Cue Title Sequence: The Body of Carrie
THIRTY YEARS AGO
The Doctor exits the TARDIS and he finds himself in the woods. He walks until he finds a car wreck with an almost dead Stephen King. Without any medical kits around, he uses what he has: himself. The Doctor uses a small bit of regenerative energy to heal the exterior damage, but he is unsure of the interior damage.
"Well, if it was anything serious, we have about an hour to get you to a hospital."
"Who are you?"
"I'm the Doctor. What happened to you, Mr. King?"
Stephen explains that he was driving across the road when he noticed a girl traveling along the road. He asked if she needs a ride, and she accepted. She got angry at something and the car went crazy and crashed itself into a tree. That's where their stories meet, with King nearly dead and the girl having gone missing.
"Well she must be here somewhere. Up you get, we'll go find her."
"Why?"
"Because there's a trail of blood going away from this car, and I want to help this mystery girl."
So the Doctor and Stephen are walking through the woods, looking for this mystery girl who Stephen mentioned called herself Carrie.
"Like your book?"
"I tried not to think about it."
Eventually, they find Carrie, standing as straight as an arrow and convulsing. The trees around her start to bend and snap, as though they were pulled by giant hands. The trees then fly towards the Doctor and Stephen. Basically, the Doctor and Stephen chase after this girl while she uses telekinesis to block their path.
This goes on until they're cornered when Carrie gives an unearthly screech and collapses to the ground. The Doctor attempts to enter her mind and sees images of a girl by the name of Jennifer Carrie enter a building. She is then in a room with her eyes forced open as she screams at a light just above her. The Doctor catches a glimpse of the sign that names the building she entered: The Institute of Mental Escapism.
The Doctor is suddenly ejected from her mind before he could enter further, and can do nothing when Carrie suddenly starts to turn into a swarm of fireflies. Before he knows it, the body of Carrie is gone.
PRESENT DAY
"And what do you want me to do with this?" the Doctor asked, "It's unfinished."
"You said to write it to that point and then ask you to finish it. You know...in all my years of being a horror novelist, I never expected to actually experience one of my supernatural stories."
"Yeah, that seems to happen whenever I cross paths with someone. Well, Stephen, I guess I'll see you thirty years ago."
"'Till we meet again, Doctor."
The Doctor goes back to his TARDIS and flips to the page where he recounts what he saw to Stephen: The Institute of Mental Escapism
Roll Credits: The Doctor Will Return in - The Institute