“What I have done, M. Poirot, is this. Mr. Templeton had a very bad attack after partaking of a bowl of soup. I took a little from the bottom of the bowl afterwards, and have brought it up with me. I have been spared for the day to visit a sick mother, as Mr. Templeton was well enough to be left.”

She drew out a little bottle of dark fluid and handed it to Poirot.

“Excellent, mademoiselle. We will have this analysed immediately. If you will return here in, say, an hour’s time I think that we shall be able to dispose of your suspicions one way or another.”

First extracting from our visitor her name and qualifications, he ushered her out. Then he wrote a note and sent it off together with the bottle of soup. Whilst we waited to hear the result, Poirot amused himself by verifying the nurse’s credentials, somewhat to my surprise.