Dorcas was looking very curiously at him and, to tell the truth, so was I. What was all this about a lost key? Poirot smiled.

“Never mind, Dorcas, it is my business to know things. Is this the key that was lost?” He drew from his pocket the key that he had found in the lock of the despatch-case upstairs.

Dorcas’s eyes looked as though they would pop out of her head.

“That’s it, sir, right enough. But where did you find it? I looked everywhere for it.”

“Ah, but you see it was not in the same place yesterday as it was today. Now, to pass to another subject, had your mistress a dark green dress in her wardrobe?”

Dorcas was rather startled by the unexpected question.

“No, sir.”

“Are you quite sure?”