“There seems no doubt that the man who was talking to Mr. Ackroyd in the library at nine-thirty could not possibly have been your son. Be of good courage, mademoiselle. All will yet be well.”

Miss Russell departed. Poirot and I were left together.

“So that’s that,” I said. “Every time we come back to Ralph Paton. How did you manage to spot Miss Russell as the person Charles Kent came to meet? Did you notice the resemblance?”