“I see,” said Hanaud, and he raised his eyebrows thoughtfully.  The Commissaire moved with impatience.

“From the middle or from the end—­what does it matter?” he exclaimed.  “The petrol was taken.”

Hanaud, however, did not dismiss the point so lightly.

“But it is very possible that it does matter,” he said gently.  “For example, if Servettaz had had no reason to examine his tins it might have been some while before he found out that the petrol had been taken.”

“Indeed, yes,” said Servettaz.  “I might even have forgotten that I had not used it myself.”

“Quite so,” said Hanaud, and he turned to Besnard.

“I think that may be important.  I do not know,” he said.

“But since the car is gone,” cried Besnard, “how could the chauffeur not look immediately at his tins?”

The question had occurred to Ricardo, and he wondered in what way Hanaud meant to answer it.  Hanaud, however, did not mean to answer it.  He took little notice of it at all.  He put it aside with a superb indifference to the opinion which his companions might form of him.

“Ah, yes,” he said, carelessly.  “Since the car is gone, as you say, that is so.”  And he turned again to Servettaz.

“It was a powerful car?” he asked.

“Sixty horse-power,” said Servettaz.

Hanaud turned to the Commissaire.

“You have the number and description, I suppose?  It will be as well to advertise for it.  It may have been seen; it must be somewhere.”

The Commissaire replied that the description had already been printed, and Hanaud, with a nod of approval, examined the ground.  In front of the garage there was a small stone courtyard, but on its surface there was no trace of a footstep.

“Yet the gravel was wet,” he said, shaking his head.  “The man who fetched that car fetched it carefully.”

He turned and walked back with his eyes upon the ground.  Then he ran to the grass border between the gravel and the bushes.

“Look!” he said to Wethermill; “a foot has pressed the blades of grass down here, but very lightly—­yes, and there again.  Some one ran along the border here on his toes.  Yes, he was very careful.”

They turned again into the main drive, and, following it for a few yards, came suddenly upon a space in front of the villa.  It was a small toy pleasure-house, looking on to a green lawn gay with flower-beds.  It was built of yellow stone, and was almost square in shape.  A couple of ornate pillars flanked the door, and a gable roof, topped by a gilt vane, surmounted it.  To Ricardo it seemed impossible that so sordid and sinister a tragedy had taken place within its walls during the last twelve hours.  It glistened so gaudily in the blaze of sunlight.  Here and there the green outer shutters were closed; here and there the windows stood open to let in the air and light.  Upon each side of the door there was a