Punctually at three o’clock next afternoon the buxom Italian maid in dainty apron, ushered me into Mrs. Cullerton’s charming salone. From the long windows a magnificent view spread away across the green valley of the Ema to the great monastery of the Certosa, a huge mediÆval pile which resembled a mediÆval fortress standing boldly against the background of the rolling Apennines.

Scarcely had I stood there a moment when my blue-eyed young hostess, in a becoming black-and-cherry frock, entered, and greeting me, closed the door.

“Well, Mr. Garfield? It’s really awfully good of you to trouble to come out to see me. I’m all excitement to know what you have to tell me about Mr. De Gex. He’s gone yachting—as you perhaps know. Do sit down.”

As I did so she passed me the cigarettes, and took one herself. Then, when I had held the match for her and had lit my own, I said:

“Well, Mrs. Cullerton, I really don’t know how to commence. Somehow, I felt it my duty to come here to see you. I must admit that I have been manoeuvring for several days in order to get an introduction to you, and to obtain an opportunity of seeing you alone. And yet——”

“Yes. I quite see that. I thought by your attitude in the Via Tornabuoni that you seemed very anxious to know me,” and her lips relaxed into a pretty smile.

“That is so. In order to—well, to warn you,” I said very seriously.

“Warn me!—of what, pray?”

I hesitated. To be perfectly frank with her was, I saw, quite impossible. She might hear all I said and then inform De Gex. She was his friend. Or perhaps she would dismiss me and my story as pure invention. Hence I resolved to preserve my own secret concerning the Stretton Street Affair.

Looking straight into her face, I said:

“I’m here to warn you of a very grave personal danger.”

“You are really most alarming, Mr. Garfield,” she said in suspicion. “In what danger am I?”

“You are either in possession of some ugly fact concerning Mr. De Gex which he desires suppressed, or else you bar his way to some ambitious achievement.”

Her face changed, and she held her breath. Though it was only for a second I saw that what I had suggested was the truth. Her slim white hand twitched nervously upon her lap.

“Some fact concerning Mr. De Gex!” she gasped in feigned surprise. “Who told you that!” she asked, her face blanching.

“I have not been told. But I know it, Mrs. Cullerton,” was my reply. “I know that, though De Gex is assisting your husband out of a financial difficulty and pretends to be your good friend, he views you as his bitter enemy—as a person whose lips must, at all hazards, be closed.”

“Really, Mr. Garfield, what you say is too extraordinary—too amazing! I don’t understand you!”

“I know it sounds most extraordinary,” I said. “But first tell me if you know a certain Doctor Moroni, who lives in the Via Cavezzo?”

“Certainly. The doctor attends Mr. De Gex and his family. I first met him in London, about a year ago. Mr. De Gex holds him in very high esteem.”

“Ah! Then you know the doctor.”

“Of course. When he was in London he several times came to our house in Fitzjohn’s Avenue.”

“And your husband knows him?” I asked, looking her straight in the face. “Please tell me the truth,” I urged.

“No. Jack has never met him—not to my knowledge.”

I was silent for a few seconds. I had established a fact which I had all along suspected.

“Then he called in the daytime, when your husband was in the City—eh?”

“Yes.”

“Now tell me, did you ever have any strange illness after Doctor Moroni had called?” I inquired very seriously.

“Illness? Why, no! Why do you ask such a curious question?”

“I have reasons for asking it, Mrs. Cullerton,” was my reply. “I have called here as your friend, remember.”

“But all this is most bewildering,” she exclaimed with a nervous little laugh. “Why should I be in any personal peril?”

“Because you know something to the detriment of that wealthy and somewhat eccentric man,” I replied. “Pardon me if I put another question to you. Are you acquainted with a girl named Gabrielle Engledue?”

“Gabrielle Engledue?” she repeated. “No, I have never heard the name. I know a Gabrielle—Gabrielle Tennison—an old schoolfellow of mine.”

“A tall, dark-haired girl?”

“Yes, she is rather tall, and dark-haired.”

“Isn’t her real name Engledue?” I asked quickly.

“Not to my knowledge.”

“Is she not Mr. De Gex’s niece?”

“He has no niece, has he?—except, of course, Lady Shalford, whom I know quite well.”

“Where is Gabrielle Tennison?”

“In London—I believe.”

“Are you certain she is not here, in Florence?”

“Mr. De Gex told me that she came to Florence for a few days——”

“To visit him—eh?”

“I suppose so. But she has returned to London.”

“Do you know her address in London,” I asked very anxiously. “I ask you this in our mutual interests, Mrs. Cullerton,” I added confidentially.

“Yes. She lives with her mother in a maisonette in Longridge Road, Earl’s Court, I forget the number, but you could easily find out.”

“And she is there now, I presume?”

“I expect so—if what Mr. De Gex has told me is the truth.”

“But will he ever tell you the truth?” I queried. “Recollect that although he poses as your husband’s friend, he is nevertheless your enemy—because he fears you! Why is that?”

The pretty wife of the young London stockbroker hesitated. I saw that she was much perturbed by my question.

“I suppose he suspects that I know certain things,” was her low, hard reply. “But he has been very good to Jack on several occasions. He has prevented him from being hammered on the Stock Exchange, therefore I can only be grateful to him.”

I looked the pretty woman straight in the face, and said:

“Grateful! Grateful to a man whose dastardly intention is, when the whim takes him, to send you to your grave, Mrs. Cullerton?”

“I—I really don’t know what you mean. Are you mad? Do be more explicit,” she cried. “Why do you make these terrible allegations against Mr. De Gex?”

“Please recollect, Mrs. Cullerton, that I am here first in your interests, and secondly in my own. You and I are now both marked down as victims, because both of us are in possession of certain knowledge which would, if exposed, bring obloquy and prosecution upon an exceedingly wealthy man. Your husband, yourself, and myself, are merely pawns in the clever game which this man is playing—a mysterious game, I admit, and one in which he is actively assisted by Doctor Moroni—but also one in which, if we are not both very wary, we shall find ourselves the victims of fatal circumstances.”

My words seemed to impress the stockbroker’s wife, for she asked: “Well—what shall I do?”

“Be perfectly frank with me,” I replied promptly. “Both of us have all to lose if we close our eyes to the conspiracy against us on the part of your friend De Gex and his shrewd and unscrupulous accomplice, Tito Moroni.”

“Moroni is one of the most popular doctors in Florence,” she remarked.

“I’m perfectly aware of that,” was my reply. “But there is no more dangerous criminal than the medical man who is beneath the thumb of a millionaire. There have been several before the assizes in various cities of Europe. Many, thanks alas! to the power of gold, have never been unmasked. There have been cases in Hungary, in France, in Italy, and in Russia—even one case in England which is recorded in a big file at Scotland Yard. But in that case there was no prosecution because money means influence, and influence means the breaking of those in office who dare to oppose it.”

“Then how do you suggest that I should act, Mr. Garfield?” asked young Mrs. Cullerton. “It is distressing news to me that Mr. De Gex is my enemy—and I confess that at present I can scarcely credit it.”

I longed to unbosom myself to her—to tell her of all that had occurred to me since that fateful November night when I had passed through Stretton Street, but I was not yet fully confident concerning her attitude towards me. It might be hostile. She might seek De Gex when he returned from Algiers and tell him of our interview! If she did, then all hope of elucidating the mystery of Gabrielle Engledue’s death would be at once swept away.

Yet I held before me the fact that the millionaire, hand-in-glove with that scoundrelly Italian, intended to cast me into my grave. The Italians have all through the centuries been experts in secret assassination. The Doges of Venice, the Borgias, and the Medici have all had secret poisoners in their pay. The gay, careless race which laughs when the sun shines, are just the same to-day, after the war, as they were in the days of His Holiness Rodrigo Borgia. To-day your superstitious Italian criminal enters the church and prays to the Madonna that his coup—whatever it may be, from profiteering, picking pockets, or the secret assassination of an enemy—may be successful.

“I allege that Mr. De Gex is your enemy, Mrs. Cullerton,” I said. “I have first-hand knowledge of it. Indeed, on the night of the ball at the Villa Clementini, he had in his pocket the wherewithal to bring upon you an illness which must inevitably prove fatal. He had a little glass tube which he had ordered Moroni to prepare, but which the doctor himself urged him not to break for fear of infecting himself and his family.”

She sat staring at me open-mouthed.

“I—I really can’t believe it!” she gasped. “Mr. De Gex would never act in such a dastardly manner towards me. We are friends—old friends.”

“You may be, but I happen to know the truth,” I declared. “He pretends friendship towards you, but his intentions are that your lips shall be closed. For some reason he fears you.”

“Are you really quite serious?” she asked, looking me full in the face.

“I certainly am,” I replied. “The reason I am here is to warn you to have a care of yourself. That some evil is intended, I know. Only I rely upon you to keep the information I have given you to yourself. Watch De Gex, but say nothing—not a word.”

“I have already promised that I will remain silent,” she remarked.

“You must also say no word to your husband. He is indebted to De Gex, hence he might tell him what I have said. And further, my name must never be mentioned to De Gex.”

“Why not?”

“He would instantly guess the source of your information.”

“But what is your motive for all this, Mr. Garfield?”

“My motive is a simple one. I am trying to find Gabrielle Engledue, and I am now wondering whether the girl I am seeking is not the same as the young lady you know as Gabrielle Tennison.”

“Where did you meet this girl Engledue?” asked Mrs. Cullerton, with a queer inquisitive look.

I paused for a second.

“In London—at the house of a mutual friend.”

Her expression caused me to ponder, for I discerned that she was inclined to doubt me.

“And why are you seeking her now?”

“I have a distinct object in view.”

“You’ve—well, perhaps you’ve fallen in love with her—eh?” she laughed lightly.

“Not at all,” I assured her. “I have a private, but very strong, motive in discovering her. I want to put to her certain questions.”

“About what, Mr. Garfield? Come, it is now my turn to be a little inquisitive,” and she laughed again.

“About a certain little matter in which we are mutually interested,” was my evasive answer. Then, after a pause, I looked straight into her eyes, and added very earnestly: “I wonder whether if I should require your help, Mrs. Cullerton, you would assist me?”

“In what way?”

“At present I cannot tell. To be frank, I am striving to solve a great and inscrutable mystery. Just now I am amazed and bewildered. But I feel that you are the only person who could help me—because you and I are equally in peril.”

“But, Mr. Garfield, I see no reason why I should be upon the brink of this mysterious abyss!” she cried. “You don’t explain the situation sufficiently fully.”

“Because at present I cannot do so. No one regrets it more than myself. There is a grim mystery—a very great mystery—and I intend, with your assistance, to escape my enemy and clear it up.”

“Who is your enemy?”

“Oswald De Gex! He is my enemy as well as yours,” I said very seriously. “If you were in the possession of such facts as those I have gathered during the past week or so, you would be startled and—well, perhaps terrified. But I only again beg of you to have a care of yourself. You have promised silence, and I, on my part, will carry on my search for the truth.”

“The truth of what?”

“The truth concerning Gabrielle Engledue.”

The pretty little woman again looked at me very straight in the face for some moments without speaking. Then, with a strange hardness about her mouth, she said:

“Mr. Garfield, take it from me, you will never discover what you are in search of. The truth is too well hidden.”

“What? Then you know something—eh?” I cried quickly.

“Yes. It is true!” she answered in a low, hard voice. “I do know something—something of a certain secret that can never pass my lips!”