it was not until the evening of the following day that harley rang me up, and:

“i want you to come round at once,” he said urgently. “the deepbrow case is developing along lines which i confess i had anticipated, but which are dramatic nevertheless.”

knowing that harley did not lightly make such an assertion, i put aside the work upon which i was engaged and hurried around to chancery lane. i found my friend, pipe in mouth, walking up and down his smoke-laden study in a state which i knew to betoken suppressed excitement, and:

“did wessex find your photographer?” i asked on entering.

“yes,” he replied. “a first-class man, as i had anticipated. as i had further anticipated he did a number of copies of the picture for the foreign gentleman—about fifty, in fact!”

“fifty!”

“yes! does the significance of that fact strike you?” asked harley, a queer smile stealing across his tanned, clean-shaven face.

“it is an extraordinary thing for even an ardent admirer to have so many reproductions done of the same picture!”

“it is! i will show you now what i found trodden into one of the footprints where the struggle took place beside the car.”

harley produced a piece of thick silk twine.

“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 tassel 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 passage with every evidence of respect. following this passage 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 twanged upon a guitar, and by most of the assembled 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.”