She thanked me and sat down. A very different type, this, from Miss Mary Marvell. Tall, dark, with flashing eyes, and a pale proud face⁠—yet something wistful in the curves of the mouth.

I felt a desire to rise to the occasion. Why not? In Poirot’s presence I have frequently felt a difficulty⁠—I do not appear at my best. And yet there is no doubt that I, too, possess the deductive sense in a marked degree. I leant forward on a sudden impulse.

“Lady Yardly,” I said, “I know why you have come here. You have received blackmailing letters about the diamond.”

There was no doubt as to my bolt having shot home. She stared at me open-mouthed, all colour banished from her cheeks.

“You know?” she gasped. “How?”

I smiled.