Together we marched down the slope of the quiet, suburban avenue; to take pause before a small, detached house displaying the hatchet boards of the estate agent. Here we found unkempt laurel bushes, and acacias run riot, from which arboreal tangle protruded the notice: "To be Let or Sold."  
Smith, with an alert glance to right and left, pushed open the wooden gate and drew me in upon the gravel path. Darkness mantled all; for the nearest street lamp was fully twenty yards beyond.
 
From the miniature jungle bordering the path, a soft whistle sounded.
 
"Is that Carter?" called Smith sharply.
 
A shadowy figure uprose, and vaguely I made it out for that of a man in the unobtrusive blue serge which is the undress uniform of the Force.
 
"Well?" rapped my companion.
 
"Mr. Slattin returned ten minutes ago, sir," reported the constable. "He came in a cab which he dismissed—"
 
"He has not left again?"
 
"A few minutes after his return," the man continued, "another cab came up, and a lady alighted."
 
"A lady!"
 
"The same, sir, that has called upon him before."
 
"Smith!" I whispered, plucking at his arm—"is
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it—?"
 
He half turned, nodding his head; and my heart began to throb foolishly. For now the manner of Slattin's campaign suddenly was revealed to me. In our operations against the Chinese murder-group two years before, we had had an ally in the enemy's camp—Kâramanèh, the beautiful slave, whose presence in those happenings of the past had coloured the sometimes sordid drama with the opulence of old Arabia; who had seemed a fitting figure for the romances of Bagdad during the Caliphate—Kâramanèh, whom I had thought sincere, whose inscrutable Eastern soul I had presumed, fatuously, to have laid bare and analysed.
 
Now once again she was plying her old trade of go-between; professing to reveal the secrets of Dr. Fu-Manchu, and all the time—I could not doubt it—inveigling men into the net of this awful fisher.
 
Yesterday, I had been her dupe; yesterday, I had rejoiced in my captivity. To-day, I was not the favoured one; to-day I had not been selected recipient of her confidences—confidences sweet, seductive, deadly: but Abel Slattin, a plausible rogue, who, in justice, should be immured in Sing Sing, was chosen out, was enslaved by those lovely mysterious eyes, was taking to his soul the lies which fell from those perfect lips, triumphant in a conquest that must end in his undoing; deeming, poor fool, that for love of him this pearl of the Orient was about to betray her master, to resign herself a prize to the victor!
 
Companioned by these bitter reflections, I had lost the remainder of the conversation between Nayland Smith and the police officer; now, casting off the succubus memory which threatened to obsess me, I put forth a giant mental effort to purge my mind of this uncleanness, and became again an active participant in the campaign against the Master—the director of all things noxious.
 
Our plans being evidently complete, Smith seized
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my arm, and I found myself again out upon the avenue. He led me across the road and into the gate of a house almost opposite. From the fact that two upper windows were illuminated, I adduced that the servants were retiring; the other windows were in darkness, except for one on the ground floor to the extreme left of the building, through the lowered venetian blinds whereof streaks of light shone out.
 
"Slattin's study!" whispered Smith. "He does not anticipate surveillance, and you will note that the window is wide open!"
 
With that my friend crossed the strip of lawn, and, careless of the fact that his silhouette must have been visible to any one passing the gate, climbed carefully up the artificial rockery intervening, and crouched upon the window-ledge peering into the room.
 
A moment I hesitated, fearful that if I followed I should stumble or dislodge some of the lava blocks of which the rockery was composed.
 
Then I heard that which summoned me to the attempt, whatever the cost.
 
Through the open window came the sound of a musical voice—a voice possessing a haunting accent, possessing a quality which struck upon my heart and set it quivering as though it were a gong hung in my bosom.
 
Kâramanèh was speaking.
 
Upon hands and knees, heedless of damage to my garments, I crawled up beside Smith. One of the laths was slightly displaced and over this my friend was peering in. Crouching close beside him, I peered in also.
 
I saw the study of a business man, with its files, neatly arranged works of reference, roll-top desk, and Milner safe. Before the desk, in a revolving chair, sat Slattin. He sat half-turned towards the window, leaning back and smiling; so that I could
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note the gold crown which preserved the lower left molar. In an armchair by the window, close, very close, and sitting with her back to me, was Kâramanèh!
 
She, who, in my dreams, I always saw, was ever seeing, in an Eastern dress, with gold bands about her white ankles, with jewel-laden fingers, with jewels in her hair, wore now a fashionable costume and a hat that could only have been produced in Paris. Kâramanèh was the one Oriental woman I had ever known who could wear European clothes; and as I watched that exquisite profile, I thought that Delilah must have been just such another as this; that, excepting the Empress Poppæ, history has record of no woman who, looking so innocent, was yet so utterly vile.
 
"Yes, my dear," Slattin was saying, and through his monocle ogling his beautiful visitor, "I shall be ready for you to-morrow night."
 
I felt Smith start at the words.
 
"There will be a sufficient number of men?"
 
Kâramanèh put the question in a strangely listless way.
 
"My dear little girl," replied Slattin, rising and standing looking down at her, with his gold tooth twinkling in the lamplight, "there will be a whole division, if a whole division is necessary."
 
He sought to take her white gloved hand, which rested upon the chair arm; but she evaded the attempt with seeming artlessness, and stood up. Slattin fixed his bold gaze upon her.
 
"So now, give me my orders," he said.
 
"I am not prepared to do so, yet," replied the girl composedly; "but now that I know you are ready, I can make my plans."
 
She glided past him to the door, avoiding his outstretched arm with an artless art which made me writhe; for once I had been the willing victim of all these wiles.
 
"But—" began Slattin.
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"I will ring you up in less than half an hour," said Kâramanèh; and without further ceremony, she opened the door.
 
I still had my eyes glued to the aperture in the blind, when Smith began tugging at my arm.
 
"Down! you fool!" he hissed sharply; "if she sees us, all is lost!"
 
Realizing this, and none too soon, I turned, and rather clumsily followed my friend. I dislodged a piece of granite in my descent; but, fortunately Slattin had gone out into the hall and could not well have heard it.
 
We were crouching around an angle of the house, when a flood of light poured down the steps, and Kâramanèh rapidly descended. I had a glimpse of a dark-faced man who evidently had opened the door for her; then all my thoughts were centred upon that graceful figure receding from me in the direction of the avenue. She wore a loose cloak, and I saw this fluttering for a moment against the white gate-posts; then she was gone.
 
Yet Smith did not move. Detaining me with his hand he crouched there against a quick-set hedge; until, from a spot lower down the hill, we heard the start of the cab, which had been waiting. Twenty seconds elapsed, and from some other distant spot a second cab started.
 
"That's Weymouth!" snapped Smith. "With decent luck, we should know Fu-Manchu's hiding-place before Slattin tells us!"
 
"But—"
 
"Oh! as it happens he's apparently playing the game." In the half-light, Smith stared at me significantly. "Which makes it all the more important," he concluded, "that we should not rely upon his aid!"
 
Those grim words were prophetic.
 
My companion made no attempt to communicate with the detective (or detectives) who shared our
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vigil; we took up a position close under the lighted study window and waited—waited.
 
Once, a taxi-cab laboured hideously up the steep gradient of the avenue.... It was gone. The lights at the upper windows above us became extinguished. A policeman tramped past the gateway, casually flashing his lamp in at the opening. One by one the illuminated windows in other houses visible to us became dull; then lived again as mirrors for the pallid moon. In the silence, words spoken within the study were clearly audible; and we heard some one—presumably the man who had opened the door—inquire if his services would be wanted again that night.
 
Smith inclined his head and hung over me in a tense attitude, in order to catch Slattin's reply.
 
"Yes, Burke," it came, "I want you to sit up until I return; I shall be going out shortly."
 
Evidently the man withdrew at that; for a complete silence followed which prevailed for fully half an hour. I sought cautiously to move my cramped limbs, unlike Smith, who seeming to have sinews of piano-wire, crouched beside me immovable, untiringly. Then loud upon the stillness, broke the strident note of the telephone bell.
 
I started, nervously, clutching at Smith's arm. It felt hard as iron to my grip.
 
"Hullo!" I heard Slattin call, "who is speaking?... Yes, yes! This is Mr. A. S.... I am to come at once?... I know where—yes!... You will meet me there?... Good!—I shall be with you in half an hour.... Good-bye!"
 
Distinctly I heard the creak of the revolving office-chair as Slattin rose; then Smith had me ............