No, Mrs. Renauld was not her husband’s murderess, But why has she lied? She lied about the wrist watch, she lied about the masked men—she lied about a third thing. Tell me, Hastings, what is your explanation of the open door?”
“Well,” I said, rather embarrassed, “I suppose it was an oversight. They forgot to shut it.”
Poirot shook his head, and sighed.
“That is the explanation of Giraud. It does not satisfy me. There is a meaning behind that open door which for a moment I cannot fathom.”
“I have an idea.” I cried suddenly.
“A la bonne heure! Let us hear it.”
“Listen. We are agreed that Mrs. Renauld’s story is a fabrication. Is it not possible, then, that Mr. Renauld left the house to keep an appointment—possibly with the murderer—leaving the front door open for his return? But he did not return. and the next morning he is found, stabbed in the back.”
“An admirable theory, Hastings, but for two facts which you have characteristically overlooked. In the first place, who gagged and bound Madame Renauld? And why on earth should they return to the house to do so? In the second place, no man on earth would go out to keep an appointment wearing his underclothes and an overcoat. There are circumstances in which a man might wear pajamas and an overcoat—but the other, never!”
“True,” I said, rather crestfallen.
“No,” continued Poirot, “we must look elsewhere for a solution of the open door mystery. One thing I am fairly sure of—they did not leave through the door. They left by the window.”
“But there were no footmarks in the flower-bed underneath.”
“No—and there ought to have been. Listen, Hastings. The gardener, Auguste, as you heard him say, planted both those beds the preceding afternoon. In the one there are plentiful impressions of his big hobnailed boots—in the other, none! You see? Someone had passed that way, someone who, to
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