“When did you first begin to suspect the maid?”

“Not for some time, but one peculiar little point drew my attention to her. The cigarette-case found in the railway carriage and which she told us was one which Mrs. Kettering had given to her husband. Now that was, on the face of it, most improbable, seeing the terms they were on. It awakened a doubt in my mind as to the general veracity of Ada Mason’s statements. There was the rather suspicious fact to be taken into consideration, that she had only been with her mistress for two months. Certainly it did not seem as if she could have had anything to do with the crime since she had been left behind in Paris and Mrs. Kettering had been seen alive by several people afterwards, but⁠—”

Poirot leant forward. He raised an emphatic forefinger and wagged it with intense emphasis at Van Aldin.