"Yes," said Locke gravely; "to-day is Tuesday."
"Tuesday, the twenty-fifth," mumbled the old man, as he consulted the book. "Yes, yes!" He returned the book to his pocket. "Very well, then, to-morrow night. Meet me in the aquarium to-morrow night at a quarter past two."
Locke, for the sake of nonchalance, carefully selected another cigarette from his case and lighted it. A quarter past two to-morrow night! If it were not pitiable, it would be absurd that the old man should have come down here in this manner to the boathouse to make an appointment for to-morrow night, when in the natural course of events he would have been afforded an endless number of infinitely more convenient opportunities to make the same request! And why to-morrow night, other than to-night, or this afternoon, or even now? And why at such an hour? It was useless to ask the question for it found its answer simply in the workings of a poor, unhinged mind—and yet Locke found himself asking the question mechanically.
"That's a rather unusual hour, isn't it, Mr. Marlin? And why to-morrow night? Why not to-night, for instance?"
The old man came close, and gripped Locke's arm again with feverish intensity. He looked all around him, then placed his lips to Locke's ear.
"I'll tell you why," he whispered. "Since last night I have been watched and followed—watched and followed all the time, all the time, all the time. They think I am mad, that my reason is gone. Ha, ha, can you imagine that, young man? Well, they will see! And so it cannot be to-night, for I must be very careful, and I must have time to prepare. And the hour? You do not understand that? Well, I will tell you something else. The hour is fixed; it cannot be altered; it cannot be changed. It is fixed." He gripped suddenly with a fiercer pressure on Locke's arm. "Ha! Did I not tell you I was always being watched and followed?" he breathed excitedly. "Listen! Listen! There is some one coming now!"
The old man was trembling violently. Locke laid his hand reassuringly upon the other's shoulder. It was quite true that there was distinctly the sound of some one's footsteps coming across one of the little bridges from the shore, the one on the far side of the boathouse from where they stood obviously, for the one on this side was in plain view.
"Why, Mr. Marlin," Locke smiled, "it's only some one coming to the boathouse. That's quite natural. There's nothing to cause you alarm in that. But just to set your mind at rest we'll go and see who it is."
"No, no!" whispered Mr. Marlin fiercely. "No one must know that I suspect anything. I can elude them—they're around on the other side now. You stay here. Don't move! I'm going now. But remember! To-morrow night! You will remember?"
"Yes; of course, Mr. Marlin," Locke replied soothingly.