*Muriel Spark, in Memento Mori (1959)
” “I wish to know something first, Mr. Holmes. What was it you spoke in Madame Schirmer’s ear which gained us entrance into her flat?”
“Oh, that,” I remarked, with a flick of the hand. “It is a simple but effective untruth, one I have used previously in similar instances; I told her that you were a dying man, and I said your wife had abandoned you in your time of need. The very fact that it was whispered should have revealed it as a lie – yet it rarely fails as a skeleton key of sorts.”
Mr. Keller stared at me with a look of slight distaste.
“Tut, man,” said I, and turned from him.”
From: A Slight Trick of the Mind (2014), by Mitch Cullin.