Poirot raised his eyebrows. “You do not use your little grey cells,” he remarked drily. “The scrap of starched cambric should be obvious.”

“Not very obvious to me.” I changed the subject. “Anyway,” I said, “this man went to the summerhouse to meet somebody. Who was that somebody?”

“Exactly the question,” said Poirot. “You will remember that Mrs. Ackroyd and her daughter came over from Canada to live here?”

“Is that what you meant today when you accused them of hiding the truth?”

“Perhaps. Now another point. What did you think of the parlour maid’s story?”

“What story?”