The Unnamable by H.P. Lovecraft isn’t much of a story as it is a justification or explanation of HPL’s own writing.
The whole piece is the account of a conversation about a piece the main character, “Carter,” wrote, in which he visits a broken down house and experiences something supernatural or demonic, depending on your worldview. The person he is telling this story to is named Manton, who is a mystic thinker and believes in many supernatural happenings. For instance, Manton believes, in the right circumstance, you can see faces in windows–the faces of people who once looked through them, and their imprints are graphed onto the glass.
This is the one point I took away from this piece to use in my own work. While I may not use it, this idea is an intriguing one. I can envision, as people become more entrenched in the world of my story, they begin to see a specific face graphed to the windows of their own homes. Perhaps these are people who have come into contact with the wrong person or have taken a drug with a sinister side effect. I’m not sure yet.
In the end, this piece just feels like an authors note to readers about what HPL is trying to accomplish, rather than a plot that evokes any kind of excitement or deep character development.