He knows when the enemy will come. Does he know for whom?
A character takes a warning seriously but protects against the wrong danger. Make the mistaken assumption shape the precautions.
Let an apparently helpful story influence how a newcomer reads the next ordinary event.
Full ending of The Open Window.
A nervous visitor knows almost nothing about the household. Vera speaks to him before her aunt arrives and asks how much he knows.
Vera describes a supposed fatal hunting accident and associates it with the open window, a coat, a dog and a repeated phrase. The living hunters return with matching details. The visitor flees, and Vera supplies another invented explanation for his flight.
Introducing unrelated supernatural evidence would change the mechanism. Avoid relying on a victim who has no plausible reason to trust or fear the story.
The Open Window: Vera tests the visitor's knowledge before her story. ↗
The Open Window and The Story-Teller only
The Open Window: Vera invents the fatal hunting accident and plants the coat, dog and repeated phrase before the hunters return. ↗
The Open Window and The Story-Teller only
The Open Window: the real hunters return, the visitor flees and Vera improvises again. ↗
The Open Window and The Story-Teller only
A storyteller who knows the household can predict details the visitor cannot. Giving those details a frightening explanation in advance prepares him to treat a later match as confirmation. The lie borrows credibility from accurate observations; the observations alone do not prove the story attached to them.
List three real details a character can predict: an arrival time, a distinctive object and a familiar phrase. Give a newcomer a false explanation connecting them. Write the predicted event normally, then let the newcomer act on the explanation. Include a plausible reason they do not check it in time.
Use in my storyA character takes a warning seriously but protects against the wrong danger. Make the mistaken assumption shape the precautions.
Introduce a capable character with missing memories by showing what they can do before asking what they know about themselves.
Build a mystery around sincere witness statements whose ordinary wording leaves out something crucial.