Tregarvon gave it up; not the lately developed notion, which grew rather more insistent the longer he thought about it, but the attempt to interest Carfax. During the lonely two-hour watch which followed he had time to go reflectively over the events of the night, to set them in orderly array, and to let the unconsidered minor happenings fit into their places and weigh as they would.

The process straightened out a few of the tangles, or it seemed to. Richardia’s concern, expressed by her fear that violence might grow out of the antagonisms, was undoubtedly for her father. Also, it was plain that up to the moment of confidences she had not suspected Hartridge of being her father’s agent; it being a fair presumption that she would have spoken of the professor if she had. Having got that far, Tregarvon began to ask himself if Hartridge was the only one actively involved. In at least two instances the schoolmaster might fairly be held exempt. It was still incredible that the man who had come to the Coalville headquarters as a guest had deliberately plotted to have his host’s motor-car wrecked on its return from Highmount. By the same token, it was difficult to imagine the professor of mathematics in the rôle of the sardonic practical joker who had shocked Rucker with a resin-filled skull, dug, doubtless, out of the old burying-ground.

On the other hand, the murderous attempt at wrecking the car and the grim joke on Rucker fitted the mountain-baron-henchman hypothesis most accurately; as did the fact, if it were a fact, that there were two persons concerned in the recent episode of the hardened steel cubes. There had been time, during the arousing of Carfax, for one man to disappear and for another to take his place; in which case it seemed evident that Hartridge had stood his ground merely to cover the retreat of the other man.

The puzzle promised to give a coherent hint pointing to its solution while Tregarvon was thinking it out and fitting the pieces together; and so long as the mental effort continued to feed the fire of wakefulness he was all that an alert sentinel should be. But after the various suppositions had been properly labelled and docketed and pigeonholed the physical reaction came, and drowsiness sat upon his shoulders, riding him like an Old Man of the Sea.

For a time he fought manfully, keeping up the struggle until he had exhausted every device he could think of and yielding only when he found himself actually falling asleep as he walked. The alternative to leaving the plant without a watchman was to call Carfax, and this he finally concluded to do. Groping his way blindly into the dark interior of the tool-shack, he stumbled over the spare coil of rope, sat down upon it for a momentary rest, and in the flitting of a bat’s wing was past help.

When he opened his eyes again the high-riding moon had swung far into the west, the glade was bathed in a ghostly flood of gray shadow, and Carfax was shaking him gently.

“Another act on,” whispered the impromptu call-boy; “no speaking parts out, as yet—only pantomime. But it is worth sitting up to see.”

Tregarvon, still sodden with sleep, suffered Carfax to lead him to the outlook window. In the gray shadows he presently made out the figure of another intruder. Within the area of the sunken graves a man, old and black, if the uncertain light could be trusted, was squatting on the ground and rocking himself back and forth, his swaying body keeping time with the measure of a weird, crooning melody. From time to time, he would stop the swaying movement to take a small white object from a basket at his side. These objects he appeared to be arranging in some sort of a figure on the ground to the accompaniment of the droning incantation.

“How long has he been there?” Tregarvon asked.

“Just a little while,” was the low-toned reply. “I awoke about half an hour ago, and when I looked out, the moon was going over to the other edge of the world, and everything was quiet. A little later the basket man came; just appeared, you know, as if he had materialized out of the shadows. When I first noticed him he was doing his little song and dance, as you see him now.”