the hour which suited me perfectly.  And, as he got out unnoticed, so he could return.  So he did return!  My friend, there are some interesting marks upon the window-sill of Wethermill’s room and upon the pillar just beneath it.  Take a look, M. Ricardo, when you return to your hotel.  But that was not all.  We talked of Geneva in Mr. Wethermill’s room, and of the distance between Geneva and Aix.  Do you remember that?”

“Yes,” replied Ricardo.

“Do you remember too that I asked him for a road-book?”

“Yes; to make sure of the distance.  I do.”

“Ah, but it was not to make sure of the distance that I asked for the road-book, my friend.  I asked in order to find out whether Harry Wethermill had a road-book at all which gave a plan of the roads between here and Geneva.  And he had.  He handed it to me at once and quite naturally.  I hope that I took it calmly, but I was not at all calm inside.  For it was a new road-book, which, by the way, he bought a week before, and I was asking myself all the while—­now what was I asking myself, M. Ricardo?”

“No,” said Ricardo, with a smile.  “I am growing wary.  I will not tell you what you were asking yourself, M. Hanaud.  For even were I right you would make out that I was wrong, and leap upon me with injuries and gibes.  No, you shall drink your coffee and tell me of your own accord.”

“Well,” said Hanaud, laughing, “I will tell you.  I was asking myself:  ’Why does a man who owns no motor-car, who hires no motor-car, go out into Aix and buy an automobilist’s road-map?  With what object?’ And I found it an interesting question.  M. Harry Wethermill was not the man to go upon a walking tour, eh?  Oh, I was obtaining evidence.  But then came an overwhelming thing—­the murder of Marthe Gobin.  We know now how he did it.  He walked beside the cab, put his head in at the window, asked, ’Have you come in answer to the advertisement?’ and stabbed her straight to the heart through her dress.  The dress and the weapon which he used would save him from being stained with her blood.  He was in your room that morning, when we were at the station.  As I told you, he left his glove behind.  He was searching for a telegram in answer to your advertisement.  Or he came to sound you.  He had already received his telegram from Hippolyte.  He was like a fox in a cage, snapping at every one, twisting vainly this way and that way, risking everything and every one to save his precious neck.  Marthe Gobin was in the way.  She is killed.  Mlle. Celie is a danger.  So Mile.  Celie must be suppressed.  And off goes a telegram to the Geneva paper, handed in by a waiter from the cafe at the station of Chambery before five o’clock.  Wethermill went to Chambery that afternoon when we went to Geneva.  Once we could get him on the run, once we could so harry and bustle him that he must take risks—­why, we had him.  And that afternoon he had to take them.”

“So that even before Marthe Gobin was killed you were sure that Wethermill was the murderer?”