Mr. Sabin received an early visitor whilst still lingering over a slight but elegant breakfast. Passmore seated himself in an easy-chair and accepted the cigar which his host himself selected for him.

“I am glad to see you,” Mr. Sabin said. “This affair of Duson’s remains a complete mystery to me. I am looking to you to help me solve it.”

The little man with the imperturbable face removed his cigar from his mouth and contemplated it steadfastly.

“It is mysterious,” he said. “There are circumstances in connection with it which even now puzzle me very much, very much indeed. There are circumstances in connection with it also which I fear may be a shock to you, sir.”

“My life,” Mr. Sabin said, with a faint smile, “has been made up of shocks. A few more or less may not hurt me.”

“Duson,” the detective said, “was at heart a faithful servant!”

“I believe it,” Mr. Sabin said.

“He was much attached to you!”

“I believe it.”

“It is possible that unwittingly he died for you.”

Mr. Sabin was silent. It was his way of avoiding a confession of surprise. And he was surprised. “You believe then,” he said, after a moment’s pause, “that the poison was intended for me?”

“Certainly I do,” the detective answered. “Duson was, after all, a valet, a person of little importance. There is no one to whom his removal could have been of sufficient importance to justify such extreme measures. With you it is different.”

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?”

Mr. Sabin looked up for a moment, but he signified his assent.

“You left America,” Passmore said, “in search of your wife, formerly Countess of Radantz, who had left you unexpectedly.”

“It is true!” Mr. Sabin answered.

“Madame la Duchesse on reaching London became the guest of the Duchess of Dorset, where she has been staying since. Whilst there she has received many visits from Mr. Reginald Brott.”

Mr. Sabin’s face was as the face of a sphinx. He made no sign.

“You do not waste your time, sir, over the Society papers. Yet you have probably heard that Madame la Duchesse and Mr. Reginald Brott have been written about and spoken about as intimate friends. They have been seen together everywhere. Gossip has been busy with their names. Mr. Brott has followed the Countess into circles which before her coming he zealously eschewed. The Countess is everywhere regarded as a widow, and a marriage has been confidently spoken of.”

Mr. Sabin bowed his head slightly. But of expression there was in his face no sign.

“These things,” Passmore continued, “are common knowledge. I have spoken up to now of nothing which is not known to the world. I proceed differently.”

“Good!” Mr. Sabin said.

“There is,” Passmore continued, “in the foreign district of London a man named Emil Sachs, who keeps a curious sort of a wine-shop, and supplements his earnings by disposing at a high figure of certain rare and deadly poisons. A few days ago the Countess visited him and secured a small packet of the most deadly drug the man possesses.”

Mr. Sabin sat quite still. He was unmoved.

“The Countess,” Passmore continued, “shortly afterwards visited these rooms. An hour after her departure Duson was dead. He died from drinking out of your liqueur glass, into which a few specks of that powder, invisible almost to the naked eye, had been dropped. At Dorset House Reginald Brott was waiting for her. He left shortly afterwards in a state of agitation.”

“And from these things,” Mr. Sabin said, “you draw, I presume, the natural inference that Madame la Duchesse, desiring to marry her old admirer, Reginald Brott, first left me in America, and then, since I followed her here, attempted to poison me.”

“There is,” Passmore said, “a good deal of evidence to that effect.”

“Here,” Mr. Sabin said, handing him Duson’s letter, “is some evidence to the contrary.”

Passmore read the letter carefully.

“You believe this,” he asked, “to be genuine?”

Mr. Sabin smiled.

“I am sure of it!” he answered.

“You recognise the handwriting?”

“Certainly!”

“And this came into your possession—how?”

“I found it on the table by Duson’s side.”

“You intend to produce it at the inquest?”

“I think not,” Mr. Sabin answered.

There was a short silence. Passmore was revolving a certain matter in his mind—thinking hard. Mr. Sabin was apparently trying to make rings of the blue smoke from his cigarette.

“Has it occurred to you,” Passmore asked, “to wonder for what reason your wife visited these rooms on the morning of Duson’s death?”

Mr. Sabin shook his head.

“I cannot say that it has.”

“She knew that you were not here,” Passmore continued. “She left no message. She came closely veiled and departed unrecognised.” Mr. Sabin nodded.

“There were reasons,” he said, “for that. But when you say that she left no message you are mistaken.”

Passmore nodded.

“Go on,” he said.

Mr. Sabin nodded towards a great vase of La France roses upon a side table.

“I found these here on my return,” he said, “and attached to them the card which I believe is still there. Go and look at it.”

Passmore rose and bent over the fragrant blossoms. The card still remained, and on the back of it, in a delicate feminine handwriting:

Mr. Passmore shrugged his shoulders. He had not the vice of obstinacy, and he knew when to abandon a theory.

“I am corrected,” he said. “In any case, a mystery remains as well worth solving. Who are these people at whose instigation Duson was to have murdered you—these people whom Duson feared so much that suicide was his only alternative to obeying their behests?”

Mr. Sabin smiled faintly.

“Ah, my dear Passmore,” he said, “you must not ask me that question. I can only answer you in this way. If you wish to make the biggest sensation which has ever been created in the criminal world, to render yourself immortal, and your fame imperishable—find out! I may not help you, I doubt whether you will find any to help you. But if you want excitement, the excitement of a dangerous chase after a tremendous quarry, take your life in your hands, go in and win.”

Passmore’s withered little face lit up with a gleam of rare excitement.

“These are your enemies, sir,” he said. “They have attempted your life once, they may do it again. Assume the offensive yourself. Give me a hint.”

Mr. Sabin shook his head.

“That I cannot do,” he said. “I have saved you from wasting your time on a false scent. I have given you something definite to work upon. Further than that I can do nothing.”

Passmore looked his disappointment, but he knew Mr. Sabin better than to argue the matter.

“You will not even produce that letter at the inquest?” he asked.

“Not even that,” Mr. Sabin answered.

Passmore rose to his feet.

“You must remember,” he said, “that supposing any one else stumbles upon the same trail as I have been pursuing, and suspicion is afterwards directed towards madame, your not producing that letter at the inquest will make it useless as evidence in her favour.”

“I have considered all these things,” Mr. Sabin said. “I shall deposit the letter in a safe place. But its use will never be necessary. You are the only man who might have forced me to produce it, and you know the truth.”

Passmore rose reluctantly.

“I want you,” Mr. Sabin said, “to leave me not only your address, but the means of finding you at any moment during the next four-and-twenty hours. I may have some important work for you.”

The man smiled as he tore leaf from his pocketbook and a made a few notes.

“I shall be glad to take any commission from you, sir,” he said. “To tell you the truth, I scarcely thought that you would be content to sit down and wait.”

Mr. Sabin smiled.

“I think,” he said, “that very shortly I can find you plenty to do.”