Burgo could not tell how long he had been asleep, for it was still pitch dark, both inside the tower and out, when he was awakened by a dull, heavy hammering noise which sounded at once remote and near at hand, as though it were close by, and yet divided from him by some intervening substance, which had the effect of partially deadening the sound. To be thus awoke in the dead of night was sufficiently startling, and Burgo sprang to his feet on the instant. After listening for the space of a few seconds, as the noise still continued, he struck a match and lighted his lamp. A glance at his watch told him that the time was twenty minutes past one.
Crossing to the door, he pushed back the slide and listened. The sound now reached him much more clearly than before, showing that it proceeded from some point inside the building--a dull, heavy, continuous thump--thump, as though someone or something were hammering a way into or out of the tower. Whence did it proceed? What could be the meaning of it? Utterly confounded, Burgo could do nothing but stand and listen.
Then, after a few minutes, which he had employed in partly dressing himself, there came a crash, and a fall as of some heavy body, followed by a confused murmur of voices. This was succeeded by a sound of many footsteps crowding up the stone stairway. Burgo drew back a few paces and waited, his eyes fixed on the aperture.
First of all the darkness of the staircase was illumined, and then a hand appeared holding on high a ship's lantern, followed by the head and figure of the man to whom the hand belonged, crowding on whose heels came three more men, each of whom carried a revolver, while one, apparently the leader, was further armed with a drawn cutlass. This last personage it was--a fair, good-looking man of thirty, with a short reddish beard and moustache, and wearing a pea-jacket and a peaked cap with a gold band--who, bringing his face into proximity with the opening, proceeded to take silent stock of Burgo and his surroundings. That what he saw filled him with surprise was evident enough from his expression. After satisfying himself that the door was locked and the key missing, he said, addressing himself to Burgo: "Pardon the question, sir, but may I ask whether you are here as a prisoner?"
"That, sir, is my unfortunate position."
"May I inquire for how long a time you have been shut up in this place?"
"For somewhere about a fortnight."
"But during the last few days you have been busy in trying to accomplish your escape?"
Burgo started. "It is quite true, but I should like to know by that means you have become aware of the fact."
The stranger smiled. "The explanation is a very simple one. I am the owner and captain of the steam yacht which you have doubtless remarked during the last few days as being anchored off shore, nearly opposite your window. Now, after having been distinctly given to understand by some of the natives, whom I questioned on the point--for I am a bit of an archaeologist, and such matters interest me--that the tower was in a semi-ruinous condition, and had been uninhabited for the last fifty years, it was certainly somewhat startling to see each evening the window lighted up from within till close on midnight, as also during several hours of each day to behold a human figure perched close against the panes, and engaged in some mysterious occupation which, for a time I was wholly puzzled to make out. At length, with the help of my binocular, I came to the conclusion that the figure was that of a man at work with a file, or some other instrument, on one of the two upright bars which safeguarded the window on its inner side. It is as a result of the knowledge thus obtained by me that you see me here at this moment."