When they reached the old garden, they bent low, approached the ruins under cover of the tallest plants, and waited a while at the foot of the wall before venturing into the entrance. Warrender kept guard on the lower floor while Armstrong, who knew the place better, explored the upper storey thoroughly with the aid of the torch, which he kept carefully shaded from outside view. Above his head, somewhere on the roof, the dismal note sounded continually. He went into the eastern room from which he had seen the signal light. No light was visible. Returning below stairs, he examined the whole of the premises with equal care. Everything was as it had been. There was nothing to indicate that any one had entered the place since his last visit.
"We shall have to make a night of it," said Warrender. "It was morning when Pratt saw some one in the lower room. It doesn't follow that he comes every morning, or, indeed, that he has ever come again; but we had better wait on the chance."
"Let us go upstairs, then, and sit against the wall where we can see the window. I don't believe that signal can be seen from the sea, and the fact that it can be seen from here seems to show that the signaller expects some one to be at the cottage. It won't be easy to keep awake, but we mustn't fall asleep together."
With backs against the wall, arms folded, and legs stretched on the floor, they sat watching. No light shone; there was no sound but those produced by the wind in the leaves and that monotonous, provoking, doleful wail from the roof. Hour after hour passed. Now and then each got up in turn to stretch his limbs. One or the other dozed at times. The still hours crept on; nothing happened; it seemed that their patience was to meet with no reward.
It was not until the faint grey tint of early dawn was stealing up the eastern horizon that a sound below caught Armstrong's attentive ear. He nudged Warrender dozing by his side. Grasping their sticks, they rose and tiptoed to the doorway. Some one was clumsily mounting the stairs. They peeped out. At the farther end of the landing a large, dark shape rose from the staircase, turned at the head, and went into the western room. Slipping off his boots, Warrender crept stealthily along the wall and looked in after the intruder. The room was dark, but, against the twilight framed by the window-opening, he saw the legs and feet of a man disappearing upwards outside. In a few moments there came scraping sounds from the roof; the moaning suddenly ceased, and after a little the man's feet reappeared; he was lowering himself into the room. Warrender stole back; at Armstrong's side he watched the man return across the landing to the staircase, and heard his heavy footsteps as he descended.
"Watch from this window; I'll go to the other," whispered Warrender.
From these posts of observation, commanding almost the whole of the surroundings of the cottage, they looked for the emergence of the visitor. He did not appear; nor, after his footsteps had ceased, did they hear a sound. Had he gone into one of the lower rooms? Leaving Armstrong to keep watch at his window, Warrender, in his stockinged feet, stole down the stairs, and peeped into each of the rooms and the kitchen and scullery in turn. The dawn was growing; but the man was not to be seen. All was silent. A slight whistle summoned Armstrong; together the boys quietly and rapidly ranged the lower floor, taking advantage of the increasing light to search for some secret hiding-place, some recess or cranny in the wall. There was nothing. The walls were too thin to enclose space enough for a man to hide. Where had he gone? He had not left the place by doorway or window; he must be somewhere within.
"The cellar!" said Armstrong, remembering the scrap of paper he had found there.
Warrender ran upstairs, slipped on his boots, and returned. The door at the head of the cellar staircase was closed. They opened it gently, listening. There was no sound from below. Cautiously, step by step, they descended. At the foot of the staircase they held their breath for a moment. Then Warrender flashed the torch. The cellar was empty. They examined every inch of the walls up to the height of a man. The brick-work was whole; not a brick was displaced, not a seam of mortar missing. They tramped over the black, dusty floor; everywhere it was solid; there was no hollow ringing beneath their feet. Scraping away a little of the coal dust, they found that the floor also was of brick except at the foot of the steps, where there was a large flagstone. Something caught Armstrong's eye. He stooped.
"Look here," he said. The joint between the flagstone and the brickwork of the floor had a sharp, well-defined edge. The crevice was free from coal dust.