“I am at monsieur’s service,” the man said in a low tone.

“Exactly. Now, Emil, before starting to visit you I left a little note behind addressed to the chief of the police here—no, you need not start—to be sent to him only if my return were unduly delayed. You can guess what that note contained. It is not necessary for us to revert to—unpleasant subjects.”

The man moistened his dry lips.

“It is not necessary,” he repeated. “Monsieur is as safe here—from me—as at his own hotel.”

“Excellent!” Mr. Sabin said. “Now listen, Emil. It has pleased me chiefly, as you know, for the sake of your wife, the good Annette, to be very merciful to you as regards the past. But I do not propose to allow you to run a poison bureau for the advantage of the Prince of Saxe Leinitzer and his friends—more especially, perhaps, as I am at present upon his list of superfluous persons.”

The man trembled.

“Monsieur,” he said, “the Prince knows as much as you know, and he has not the mercy that one shows to a dog.”

“You will find,” Mr. Sabin said, “that if you do not obey me, I myself can develop a similar disposition. Now answer me this! You have within the last few days supplied several people with that marvelous powder for the preparation of which you are so justly famed.”

“Several—no, monsieur! Two only.”

“Their names?”