The Overlooked Detail

I first came across this technique while reading The Exorcist (being a horror wimp, I nearly always read the book before I subject myself to the movie). In that book, an interesting little thing occurs early in the story. Reagan is already beginning to show the early symptoms of her possession, but the thing has not yet blossomed into full flower.

The author (Peter Blatty) makes passing reference to the fact that there is a book on the bookshelf in the downstairs study. I don't even recall the exact topic of the book, although I believe it has something to do with supernatural phenomena.

At one point, the author simply states that the book in question is now missing from the bookshelf, and he ends with the words: "Nobody noticed."

In Stephen King's Misery, a similar thing happens when the trapped author ventures out of his room while his captor is away from the house. It's a very dangerous thing for him to do, since she will undoubtedly do something horrible to him if she discovers that he has trespassed outside of his allowed space in the house.

He makes it back into his room well before her return, and he is congratulating himself on "getting away with it." But as he re-enters his room, his wheelchair scrapes against the door, leaving a tell-tale mark on the door. We know that the mark is there, and we know that she will find it. But our hero remains completely unaware that he has left this crucial clue behind.

This notion of the crucial overlooked detail is useful because it reveals the chinks in the hero's/heroine's armor and gives the reader the sense that the hero/heroine is more vulnerable than s/he fully appreciates.