My back view, head sunk forward, shoulders humped up, gave, I believe, a convincing picture of utter abasement as I slowly retraced my steps down the ravine. But the moment I was out of sight of the ill-favoured group about the rock, I darted into the thickest part of the jungle and, after dragging myself painfully through the undergrowth for about a hundred yards, sank down hot and breathless.  
I did not care whether I was followed or not. I wanted to be alone to compose my thoughts, to think. My brain was still reeling beneath the shock of my stupendous good fortune. Five minutes since I would scarcely have given a sixpence for my chances of life. Yet here I had regained my freedom of action, had lulled old Clubfoot, by giving him an easy victory, into a false sense of security and, at the same time, had obtained the solution of the knottiest point of the whole cipher message. At the thought that it was Grundt himself who had given me the clue which, till then, I had vainly sought, I leant back and laughed.
 
"After the Somme and the Hindenburg Line," he had said, "our brave 'eighty-fivers' dislike you British even as much as our sailor-men do...."
 
"Unsere braven Fünf-und-Achtziger" .... he had used the German phrase and in a flash brought back to my mind a bit of German naval slang which I had heard so long ago that I had forgotten it! "Die Fünf-und-Achtziger!" What memories of pre-war days the phrase awakened! Dinner at Kiel in the ward-room of the German flagship, the tables ablaze with blue and gold uniforms sparkling with decorations, guest night in the mess of the Kaiser Franz Hussars at Stettin.... and always army and navy "shop" the staple theme of our table talk. To the Imperial Navy the German Army was (slightly superciliously, for the rivalry between the two was intense) "die Fünf-und-Achtziger" because the 85th Infantry Regiment composed the garrison of Kiel, Germany's premier war-harbour.
 
The garrison of Kiel! Clubfoot, like all his master's entourage, was in closest touch with the Fleet, the Kaiser's own creation. That scrap of navy slang came naturally to his lips and in uttering it, he had sent with a flash the cipher to my mind.
 
"Flimmer', flimmer' viel"
"Die Garnison von Kiel"
 
The garrison of Kiel represented the figure "85." How, then, did the cipher run en clair?
 
Heliograph
85
Compass bearing of 27 degrees.
 
Eighty-five, I realised at once, was the angle for the heliograph. The message, therefore, read:—
 
"Turn the heliograph at an angle of 85 degrees (i.e., from the horizontal since it had been wired so as only to be raised or lowered) on a compass bearing of 27 degrees...."
 
The weight of the little mirror in my jacket pocket heartened me immensely. Clubfoot, I knew, would see the figure "85" in the allusion to the Kiel garrison. But the mirror was the starting-point for the whole cipher. And he had never known that a mirror was on the grave! The mirror, fixed in position as I had found it, made the first half of the message as clear as day. Without this essential pointer the cipher itself would be useless to Clubfoot. Even if his remarkably astute brain should divine the allusion to a heliograph in that first line, he would not have the mirror....
 
In any case, his investigations would be delayed. And I was playing for time. Six days must elapse, I reflected, before the yacht could return. For how many of these would I continue to enjoy my liberty? For as soon as Clubfoot realised that he had been fooled, I knew that he would once again stretch out that long arm of his to seize me. I should have to find a secure hiding-place—I thought of the high ground of the island, somewhere among those lofty volcanic peaks, in this connection—but the present need was for action. In the light of the fresh clue I had obtained, I must push on with my investigation at the grave itself and that without a moment's delay. For the rest of the cipher, notably those baffling bars of music, which were firmly fixed in my mind,—well, sufficient for the day is the evil thereof!
 
I looked at my watch. It was twenty minutes past eleven. "Mittag"—noon—the message was dated, clearly an indication of the time at which the experiment with the heliograph was to be made. If I were to act, I must act at once. Fortunately, the grave could not be far from where I lay. But what of Clubfoot?
 
The sound of voices came as if in answer to my query—of voices close at hand. Parting the foliage in front of me, I saw a file of men winding their way through the forest not twenty paces away. They appeared to be following some kind of path; for they marched steadily, one behind the other.
 
I pressed myself flat behind my protecting bush, only my head raised to observe the men as they went by. Now scraps of German came to my ears. There was talk of someone they called "Red Itzig," a Jew, who was to read the cipher for them. Itzig was apparently ill for there was some chaff about "the Jew" being cured as soon as he could hear that the treasure was within their grasp.
 
Did this mean that they were going back to their camp? And that the coast was clear for that pressing work I had to do. Five minutes, I calculated, would suffice for my purpose.
 
I kept a sharp eye open for Clubfoot. Here he came, the eighth in the party, hobbling along in the rear, with set face, grim and silent. The line halted for a moment. The man in front of Clubfoot, a small, dark man, doffed his panama to sponge his face. To my amazement it was Custrin.... Custrin, whom I had last seen, at the side of Marjorie Garth, standing at the head of the Naomi's ladder waving us farewell as the launch took us ashore....
 
Now I had the solution of something that had greatly puzzled me—Clubfoot's exact knowledge of where I kept the cipher message, his allusion to my "Government survey work" on Cock Island. Then Custrin was one of El Cojo's spies! With a little shiver I thought of that hocussed drink. What would have been my fate that night but for the merciful intervention of Providence? I could make a pretty shrewd guess. They would have found me insensible in my berth and Custrin gone in the morning—in one of the ship's boats. I wondered vaguely what had become of the doctor whose papers he must have appropriated....
 
The voices had died away now and Clubfoot, the last of the line, had disappeared from my sight. I had counted eight in the party. All, therefore, seemed to have passed. Softly I began to wriggle myself forward....
 
I reached the path which the party had followed. It was a well-marked track through the forest. The trees were not so dense here, and above my head I caught at intervals a glimpse of dazzling blue sky. The sun was very hot.
 
Quietly and quickly I went down the track, heading for the direction from which Clubfoot and his men had come. I went warily, bitterly conscious of my defenceless state. But I met no one and presently I stood on the edge of the clearing, the grave of the Unknown below me.
 
The clearing was all a-quiver with heat; gorgeous-hued butterflies danced from bush to bush amid flaming flowers; the drone of insects was in the air. I skirted the edge of the basin, then silently dropped down to the grave.
 
I took out the little mirror and gave it a good rub-up with my handkerchief. Then, going down on my knees, I laid it on the grave as I had originally found it—face upwards with the holes in the frame aligned with the holes in the timber baulk beneath. With my compass I took my bearing of 27 degrees, ad............