“I notice that Duson was found in your sitting-room. It occurs to me as a possibility that he may have met with a fate intended for some one else—for yourself, for instance, sir!”

“But I,” Mr. Sabin said smoothly, “am a member of no secret society, nor am I conscious of having enemies sufficiently venomous to desire my life.”

The detective sat for a moment with immovable face.

“We, all of us, know our friends, sir,” he said. “There are few of us properly acquainted with our enemies.”

Mr. Sabin lit a cigarette. His fingers were quite steady, but this man was making him think.

“You do not seriously believe,” he asked, “that Duson met with a death which was intended for me?”

“I am afraid,” the detective said thoughtfully, “that I know no more about it than you do.”

“I see,” Mr. Sabin said, “that I am no stranger to you.”

“You are very far from being that, sir,” the man answered. “A few years ago I was working for the Government—and you were not often out of my sight.”

Mr. Sabin smiled.