"Here you are, Petrie," said Nayland Smith—and he tossed across the table the folded copy of a morning paper. "This may assist you in your study of the first Zagazig message."  
I set down my cup and turned my attention to the "Personal" column on the front page of the journal. A paragraph appeared therein conceived as follows:—
 
ZAGAZIG-Z-a-g-a;-z:-I:-g;z-a,g;-
  A-,z;i:G,-z:a;g-A,z-i;-gz
  A;_g_aZ-i;g-:a z i g
 
I stared across at my friend in extreme bewilderment.
 
"But, Smith!" I cried, "these messages are utterly meaningless!"
 
"Not at all," he rapped back. "Scotland Yard thought they were meaningless at first, and I must admit that they suggested nothing to me for a long time; but the dead dacoit was the clue to the first, Petrie, and the note pinned upon the door of the house near the Oval is the clue to the second."
 
Stupidly I continued to stare at him until he broke into a grim smile.
 
"Surely you understand?" he said. "You remember where the dead Burman was found?"
 
"Perfectly."
 
"You know the street along which, ordinarily, one would approach the wharf?"
 
"Three Colt Street?"
 
"Three Colt Street, exactly. Well, on the night that the Burman met his end I had an appointment in Three Colt Street with Weymouth. The appointment was made by 'phone, from the New Louvre! My cab broke down and I never arrived. I discovered later that Weymouth had received a telegram purporting to come from me, putting off the engagement."
 
"I am aware of all this!"
 
Nayland Smith burst into a loud laugh.
 
"But still you are fogged!" he cried. "Then I'm hanged if I'll pilot you any farther! You have all the facts before you. There lies the first Zagazig message; here is the second; and you know the context of the note pinned upon the door? It read, if you remember, 'Remove patrol from Joy-Shop neighborhood. Have a theory. Wish to visit place alone on Monday night after one o'clock.'"
 
"Smith," I said dully, "I have a heavy stake upon this murderous game."
 
His manner changed instantly; the tanned face grew grim and hard, but the steely eyes softened strangely. He bent over me, clapping his hands upon my shoulders.
 
"I know it, old man," he replied; "and because it may serve to keep your mind busy during hours when otherwise it would be engaged with profitless sorrows, I invite you to puzzle out this business for yourself. You have nothing else to do until late to-night, and you can work undisturbed, here, at any rate!"
 
His words referred to the fact that, without surrendering our suite at the New Louvre Hotel, we had gone upon a visit, of indefinite duration, to a mythical friend; and now were quartered in furnished chambers adjoining Fleet Street.
 
We had remained at the New Louvre long enough to secure confirmation of our belief that a creature of Fu-Manchu spied upon us there; and now we only awaited the termination of the night's affair to take such steps as Smith might consider politic in regard to the sardonic Greek who presided over London's newest and most palatial hotel.
 
Smith setting out for New Scotland Yard in order to make certain final arrangements in connection with the business of the night, I began closely to study the mysterious Zagazig messages, determined not to be beaten, and remembering the words of Edgar Allan Poe—the strange genius to whom we are indebted for the first workable system of deciphering cryptograms: "It may well be doubted whether human ingenuity can construct an enigma of the kind which human inge............