Mr. Sabin knocked the ash from his cigarette.

“Why not be frank with me, Mr. Passmore?” he said. “There is no need to shelter yourself under professional reticence. Your connection with Scotland Yard ended, I believe, some time ago. You are free to speak or to keep silence. Do one or the other. Tell me what you think, and I will tell you what I know. That surely will be a fair exchange. You shall have my facts for your surmises.”

Passmore’s thin lips curled into a smile. “You know that I have left Scotland Yard then, sir?”

“Quite well! You are employed by them often, I believe, but you are not on the staff, not since the affair of Nerman and the code book.”

If Passmore had been capable of reverence, his eyes looked it at that moment.

“You knew this last night, sir?”

“Certainly!”

“Five years ago, sir,” he said, “I told my chief that in you the detective police of the world had lost one who must have been their king. More and more you convince me of it. I cannot believe that you are ignorant of the salient points concerning Duson’s death.”

“Treat me as being so, at any rate,” Mr. Sabin said.

“I am pardoned,” Passmore said, “for speaking plainly of family matters—my concern in which is of course purely professional?”