Agatha Christie: The Mysterious Affair at Styles

CHAPTER 5. "IT ISN'T STRYCHNINE, IS IT?" (continued)

"Perfectly. Put with admirable clearness. Proceed."

"Well," I said, encouraged, "as the person who entered did not do so by the window, nor by miraculous means, it follows that the door must have been opened from inside by Mrs. Inglethorp herself. That strengthens the conviction that the person in question was her husband. She would naturally open the door to her own husband."

Poirot shook his head.

"Why should she? She had bolted the door leading into his room--a most unusual proceeding on her part--she had had a most violent quarrel with him that very afternoon. No, he was the last person she would admit."

"But you agree with me that the door must have been opened by Mrs. Inglethorp herself?"

"There is another possibility. She may have forgotten to bolt the door into the passage when she went to bed, and have got up later, towards morning, and bolted it then."

"Poirot, is that seriously your opinion?"

"No, I do not say it is so, but it might be. Now, to turn to another feature, what do you make of the scrap of conversation you overheard between Mrs. Cavendish and her mother-in-law?"

"I had forgotten that," I said thoughtfully. "That is as enigmatical as ever. It seems incredible that a woman like Mrs. Cavendish, proud and reticent to the last degree, should interfere so violently in what was certainly not her affair."

"Precisely. It was an astonishing thing for a woman of her breeding to do."

"It is certainly curious," I agreed. "Still, it is unimportant, and need not be taken into account."

A groan burst from Poirot.

"What have I always told you? Everything must be taken into account. If the fact will not fit the theory--let the theory go."