"What is it?"

"It is a link, Knox--a link to seek which I really went down to Deepbrow." He stared at me quizzically, but my answering look must have been a blank one. "It is part of the ta.s.sel of one of those red cloth caps commonly called in England, a fez!"

He continued to stare at me and I to stare at the piece of silk; then:

"What is the next move?" I demanded. "Your new clue rather bewilders me."

"The next move," he said, "is to retire to the adjoining room and make ourselves look as much like a couple of Oriental commercial travellers as our correctly British appearance will allow!"

"What!" I cried.

"That's it!" laughed Harley. "I have a perpetual tan, and I think I can give you a temporary one which I keep in a bottle for the purpose."

Twenty minutes later, then, having quitted Harley's chambers by a back way opening into one of those old-world courts which abound in this part of the metropolis, two quietly attired Eastern gentlemen got into a cab at the corner of Chancery Lane and proceeded in the direction of Limehouse.

There are haunts in many parts of London whose very existence is unsuspected by all but the few; haunts unvisited by the tourist and even unknown to the copy-hunting pressman. Into a quiet thoroughfare not three minutes' walk from the busy life of West India Dock Road, Harley led the way. Before a door sandwiched in between the entrance to a Greek tobacconist's establishment and a boarded shop-front, he paused and turned to me.

"Whatever you see or hear," he cautioned, "express no surprise. Above all, show no curiosity."

He rang the bell beside the door, and almost immediately it was opened by a Negress, grossly and repellently ugly.

Harley pattered something in what sounded like Arabic, whereat the Negress displayed the utmost servility, ushering us into an ill-lighted pa.s.sage with every evidence of respect. Following this pa.s.sage to its termination, an inner door was opened, and a burst of discordant music greeted us, together with a wave of tobacco smoke. We entered.

Despite my friend's particular injunctions to the contrary I gave a start of amazement.

We stood in the doorway of a fairly large apartment having a divan round three of its sides. This divan was occupied by ten or a dozen men of mixed nationalities--Arabs, Greeks, lascars, and others. They smoked cigarettes for the most part and sipped Mokha from little cups. A girl was performing a wriggling dance upon the square carpet occupying the centre of the floor, accompanied by a Nubian boy who tw.a.n.ged upon a guitar, and by most of the a.s.sembled company, who clapped their hands to the music or droned a low, tuneless dirge.

Shortly after our entrance the performance terminated, and the girl retired through a curtained doorway at the farther end of the room.

Our presence being now observed, suspicious glances were cast in our direction, and a very aged man, who sat smoking a narghli near the door by which the girl had made her exit, gravely waved towards us the amber mouthpiece which he held in his hand.

Harley walked straight across to him, I close at his heels. The light of a lamp which hung close by fell fully upon my friend's face; and, rising from his seat, the old man greeted him with the dignified and graceful salutation of the East. At his request we seated ourselves beside him, and, while we all three smoked excellent Turkish cigarettes, Harley and he conversed in a low tone. Suddenly, at some remark of my friend's, our strange host rose to his feet, an angry frown contracting his heavy eyebrows.

Silence fell upon the company.

In a loud and peremptory voice he called out something in Arabic.

Instantly I detected a fellow near the entrance door, and whom I had not hitherto observed, slipping furtively into the shadow, with a view, as I thought, to secret departure. He seemed to be deformed in some way and had the most evil, pock-marked face I had ever beheld in my life.

Angrily, the majestic old man recalled him. Whereupon, with a sort of animal snarl quite indescribable, the fellow plucked out a knife! Two men who had been on the point of seizing him fell back, and:

"Hold him!" shouted Harley, springing forward--"hold him! It's Ali of Cairo!"

But Harley was too late. Turning, the strange and formidable-looking Oriental ran like the wind! Ere hand could be raised to stay him he was through the doorway!

"That settles it," said Harley grimly, as once more I found myself in a cab beside him. "I was right; but he'll forestall us!"

"Who will forestall us?" I asked in bewilderment.

"The biggest villain in Europe, Asia, or Africa!" cried my companion.

"I have wasted precious time to-day. I might have known." He drummed irritably upon his knees. "The place we have just left is a sort of club, you understand, Knox, and Hakim is the proprietor or host as well as being an old gentleman of importance and authority in the Moslem world. I told him of my suspicions--which step I should have taken earlier--and they were instantly confirmed. My man was there--recognized me--and bolted! He'll forestall us."

"But my dear fellow," I said patiently--"who is this man, and what has he to do with the Deepbrow case?"

"He is the blackest scoundrel breathing!" answered Harley bitterly. "As to what he has to do with the case--why did he bolt? At any rate, I know where to find him now--and we may not be too late after all."

"But who and what is this man?"

"He is Ali of Cairo! As to what he is--you will soon learn."

IV

THE HOUSE BY THE RIVER

On quitting the singular Oriental club, Harley had first raced off to a public telephone, where he had spoken for some time--as I now divined--to Scotland Yard. For when we presently arrived at the headquarters of the Metropolitan Police, I was surprised to find Inspector Wess.e.x awaiting us. Leaning out of the cab window:

"Yes?" called Harley excitedly. "Was I right?"

"You were, Mr. Harley," answered Wess.e.x, who seemed to be no less excited than my companion. "I got the man's reply an hour ago."

"I knew it!" said Harley shortly. "Get in, Wess.e.x; we haven't a minute to waste."

The Inspector joined us in the cab, having first given instructions to the chauffeur. As we set out once more:

"You have had very little time to make the necessary arrangements,"

continued my friend.

"Time enough," replied Wess.e.x. "They will not be expecting us."

"I'm not so sure of it. One of the biggest villains in the civilized world recognized me three minutes before I called you up and then made good his escape. However, there is at least a fighting chance."

Little more was said from that moment until the end of the drive, both my companions seeming to be consumed by an intense eagerness to reach our destination. At last the cab drew up in a deserted street. I had rather lost my bearings; but I knew that we were once more somewhere in the Chinatown area, and:

"Follow us until we get into the house," Harley said to Inspector Wess.e.x, "and wait out of sight. If you hear me blow this whistle, bring up the men you have posted--as quick as you like! But make it your particular business to see that no one gets out!"

Into a pitch-dark yard we turned, and I felt a shudder of apprehension upon observing that it was the entrance to a wharf. Dully gleaming in the moonlight, the Thames, that grave of many a ghastly secret, flowed beneath us. Emerging from the shadow of the archway, we paused before a door in the wall on our left.

At that moment something gleamed through the air, whizzed past my ear, and fell with a metallic jingle on the stones!

Instinctively we both looked up.

At an unlighted window on the first floor I caught a fleeting glimpse of a dark face.

"You were right!" I said. "Ali of Cairo has forestalled us!"

Harley stooped and picked up a knife with a broad and very curious blade. He slipped it into his pocket, nonchalantly.