“Ah!” Schilder blinked before the sudden radiance. “The dynamo must have slipped a belt, or——” He halted, with a little gasp. “Why,” he exclaimed, “what has become of the colonel?”

It was certainly astonishing. Not one of the three other occupants of the room had stirred. Grail and the manager stood in exactly the same position as before, and the stenographer still sat at her table with her fingers resting on the keys of her typewriter, but the colonel was gone.

With a common impulse, the two men stepped swiftly to the door, and glanced out across the yard. There had not been sufficient time for any one to cross it and reach the gate, yet the colonel was nowhere to be seen, and his erect, soldierly figure could not possibly have gone unrecognized in that wide-open space, and under the glare of the half dozen or more arc lamps now brightly burning. Nor could there be any question of his having strayed from the direct path in the darkness and being now hidden from their view by a pile of rubbish or material, for the inclosure was remarkably free from obstruction. Indeed, the last of what had been a towering scrap heap was being cleaned up, and, with the aid of an electric crane, loaded on cars by the force of men then at work.

“Well, what do you know about that!” Schilder muttered. Then, closely followed by Grail, he hurried across the yard to interrogate the old watchman at the gate. But the latter was firm in his protestation that no one had passed him. Even with the yard lights all out, he could still, he declared, have seen anybody leaving the place by the illumination from the street lamp on the corner.

“Then,” said Grail, “he must have gone out some other way.”

The manager waved his hand significantly toward the high board fence which completely surrounded the yard, and which was topped with sharp spikes to keep out pilferers. There was but one exit—the gate at which they had already made inquiry; the big doors leading into the foundry building were barred and padlocked.

“Perhaps he is still in the office,” ventured Grail. “He might have had a seizure of some kind in the darkness, you know, and fallen behind a piece of furniture.”

But even as he voiced the suggestion he realized its utter absurdity. Schilder’s office contained nothing except the desk which could have concealed the body of a man, and the desk was pushed back close against the wall. Nevertheless, they made an inspection of the place, but entirely without result. Then, when the manager called in every man working in the yard, and questioned him, to no purpose, the searchers seemed to have come to the end of their tether.

“But it is preposterous, you know!” exclaimed Grail, attempting to throw off his misgivings. “There is, of course, some absolutely simple explanation, and the colonel is, no doubt, out at the post by this time, swearing about me for not putting in an appearance. May I use your telephone, Mr. Schilder?”

Inquiry at the fort elicited that Colonel Vedant had not returned, and no information regarding him could be gained from his quarters, the club, or any of his customary haunts. When Grail had gone through the entire list, and called up the post again, only to receive the same negative answer, he made no effort to conceal his growing anxiety. A suspicion of foul play strengthened in his mind. “If not that,” he asked, “why should the colonel, of his own accord, disappear in this absurdly mysterious manner? Colonel Vedant is not the sort of man to be waylaid or carried off without making at least a show of resistance, and I certainly heard no outcry or sound of a struggle. Did you?”