It isn't a true story. 'Devil's Doorway' is likely a product of the creator's imagination, crafted to engage and thrill the audience with a made-up plot and characters.
In 'every heart a doorway novel', Nancy is a prominent character. She's a young girl with a past in another world. Then there are her fellow students at the school. For example, there's a character who had an experience in a very strange and magical world and now is trying to come to terms with being back in a more ordinary setting. Another character might have been to a dark and foreboding world and has a certain air of mystery about them. All these characters, with their diverse experiences, make up the rich tapestry of the story.
The main theme in 'every heart a doorway novel' is centered on the journey of self - discovery. These characters who have traversed other worlds are now on a path to understand themselves better. They carry the memories and experiences of those other places, and it has a profound impact on who they are. It shows how these experiences shape their sense of self and their search for a place where they can be truly at home, both in their hearts and in the physical world.
I'm not sure which specific 'I am the doorway' story you are referring to. It could be a very unique or personal narrative, or perhaps from a particular book or cultural context that I'm not familiar with.