I didn't know then, and I don't know now, whether she was the owner of the world's best poker face or was just naturally stupid, but whichever she was, she was thoroughly and completely it.
Source, in full
"Women, Politics and Murder" (published in Black Mask, September 1924; retitled "Death on Pine Street" when reprinted in the first anthology of Continental Op stories, The Continental Op, published in 1945; subsequent reprintings have used the latter title for this story)