“Perhaps he only passed through here to go to you.”

“To me, Monsieur le Prefet?  I was in my room all the time.”

“Then it’s incomprehensible.”

“Yes ... unless we conclude that the messenger’s attention was distracted for a second, as Verot is neither here nor next door.”

“That must be it.  I expect he’s gone to get some air outside; and he’ll be back at any moment.  For that matter, I shan’t want him to start with.”

The Prefect looked at his watch.

“Ten past five.  You might tell the messenger to show those gentlemen in....  Wait, though—­”

M. Desmalions hesitated.  In turning over the papers he had found Verot’s letter.  It was a large, yellow, business envelope, with “Cafe du Pont-Neuf” printed at the top.

The secretary suggested: 

“In view of Verot’s absence, Monsieur le Prefet, and of what he said, it might be as well for you to see what’s in the letter first.”

M. Desmalions paused to reflect.

“Perhaps you’re right.”

And, making up his mind, he inserted a paper-knife into the envelope and cut it open.  A cry escaped him.

“Oh, I say, this is a little too much!”

“What is it, Monsieur le Prefet?”

“Why, look here, a blank ... sheet of paper!  That’s all the envelope contains!”

“Impossible!”

“See for yourself—­a plain sheet folded in four, with not a word on it.”

“But Verot told me in so many words that he had said in that letter all that he knew about the case.”

“He told you so, no doubt, but there you are!  Upon my word, if I didn’t know Inspector Verot, I should think he was trying to play a game with me.”

“It’s a piece of carelessness, Monsieur le Prefet, at the worst.”

“No doubt, a piece of carelessness, but I’m surprised at him.  It doesn’t do to be careless when the lives of two people are at stake.  For he must have told you that there is a double murder planned for to-night?”

“Yes, Monsieur le Prefet, and under particularly alarming conditions; infernal was the word he used.”

M. Desmalions was walking up and down the room, with his hands behind his back.  He stopped at a small table.

“What’s this little parcel addressed to me?  ’Monsieur le Prefet de Police—­to be opened in case of accident.’”

“Oh, yes,” said the secretary, “I was forgetting!  That’s from Inspector Verot, too; something of importance, he said, and serving to complete and explain the contents of the letter.”

“Well,” said M. Desmalions, who could not help laughing, “the letter certainly needs explaining; and, though there’s no question of ‘accident,’ I may as well open the parcel.”

As he spoke, he cut the string and discovered, under the paper, a box, a little cardboard box, which might have come from a druggist, but which was soiled and spoiled by the use to which it had been put.