When Richard Duvall once more opened his eyes, he saw nothing but a blinding glare of light, that hurt and bewildered him with its singular and brilliant intensity. He closed his eyes again at once, unable to bear the irritation which was thus caused him. It was not exactly pain that he felt, but an intense discomfort, such as one experiences when looking directly at the brilliant rays of the sun.

After a few moments spent in futile attempts to cover his eyes with his hands, only to discover that his arms were tightly bound, he thought to secure relief by turning his face to one side, so that his vision might seek the soft darkness which seemed to lie on every side of him. In this effort he was equally unsuccessful. His head, his neck, his whole body, were rigid, immovable. He could not stir an inch in any direction.

He spent a long time in useless speculation upon the meaning of the remarkable situation in which he now found himself. He felt no pain, no discomfort, except that which the brilliance of the light above him caused. He determined at length once more to open his eyes, in order to discover if possible its source.

Even when his eyes were closed, he could see that the strange light burnt upon them. In a way it rendered his eyelids translucent—he was conscious of a dull pulsing redness through which shot a network of lines of fire. He opened his eyes slowly, cautiously, and looked upward. From some point above him, in what he judged must be the ceiling of the room, extended a beam of violet white light, cutting sharply through the darkness like the rays of a searchlight. At the opening in the ceiling through which it came, this beam was in diameter not more than two inches, but as it extended downward, it widened, taking the form of a long, thin, truncated cone, so that its width, where it impinged upon his face, was perhaps equal to twice that of a man's hand.

The darkness of the room about him made the beam of light seem a tangible, material thing. Its brilliance was unwavering—it extended from the ceiling to the surface of his face with the solidity, almost, of some huge, glittering icicle. He felt as though, were his hands but free, he could brush it aside, fling it off bodily into the darkness.

The effort of looking directly at the source of the light made his eyes smart with pain, but he found that by half-closing them, he could look off into the darkness, through the brilliant cone. In the pathway of its rays danced and tumbled innumerable dust specks—he knew then but for their presence, to afford the light a reflecting surface, its rays would be invisible to him.

In color the light was not yellow, like sunlight, but had a cold violet-blue quality, more nearly resembling moonlight. Its intensity, as well as the shape of the light cone, made him conclude that it was being focused through a powerful lens, or projected by means of a brilliant reflector.

He could imagine no possible reason for the situation in which he found himself. What the purpose of the beam of light was; why it thus focused upon his upturned face, he could not guess. He thought about it for many minutes, his eyes closed, his head straining restlessly toward the soft outer darkness. Presently there flashed into his mind Dr. Hartmann's words at their last meeting: "While I know how to cure mental disorders, I also know how to create them." The thought made him shudder. Was this, then, the explanation of his predicament? Somewhere he had read, not long before, a newspaper account of the investigations of certain Italian scientists, concerning the effect of the violet and ultra-violet light rays upon the cells of the brain. He could not recollect just what the conclusions had been, but he did remember that the newspaper article spoke of the popular superstition that moonlight could cause insanity. He knew Hartmann to be a scientist of vast ability and resource, and realized that back of the elaborate preparations he had evidently made must lie some sinister purpose.

For what seemed an eternity he lay thinking, unable to come to any rational conclusion. The distressing effect of the light rays increased, rather than diminished, as his nerves became more and more unstrung. It seemed, even with, his eyes closed, that he could feel the weight of the cone of light upon his face. The desire to escape from its searching glare became well-nigh irresistible. How long would this torture continue? He began to feel intensely tired and worn out and realized that could he but shut out the blinding brilliancy which enveloped him, he would sink exhausted to sleep. Sleep! He could no more sleep, under the present conditions, than he could fly to the moon. Then there came to his mind a recollection of a form of torture practised among the Chinese, the prevention of sleep. Prisoners, he had read, were confined in a cage, in brilliant sunlight, and prevented from sleeping by being prodded from without with spears. At the expiration of a week, he had read, the victim goes raving mad. Was this, then, Hartmann's intention?

Whatever the man did, he knew he would adopt only such methods as would involve him in no damaging consequences. He might be kept in his present situation until insanity ensued, and Hartmann with his reputation as a physician, a scientist, could calmly deny any story he might tell, putting it down to the wanderings of a disordered brain. He realized the cunning of the man, his care to use no physical violence. Should he, Duvall, under the strain of the torture which he realized lay before him, consent to disclose the whereabouts of the ivory snuff box, in return for his liberty, what could he do, in retaliation? Hartmann would calmly deny his story, and would doubtless produce witnesses, such as Mayer, to prove that the detective came to him for treatment for some slight mental disorder, some lapse of memory and that the exposure to the light rays had been but part of his usual treatment. Clearly the doctor had covered his tracks most successfully.

Throughout all these torturing thoughts, the figure of Grace came and went unceasingly. What would she do—what could she do, to aid him? He had warned her not to ask Mr. Phelps to take any steps looking to his release. He realized that were Hartmann to appear now, and give him his freedom, he would not dare to accept it. That the doctor might do this very thing was his greatest fear. If he should insist upon his leaving the place, what could he do, then, to recover Monsieur de Grissac's snuff box? He prayed fervently that Dufrenne and his companions might in some way work out a plan to set matters right.

Presently he fell to thinking of the snuff box, and its safety. How fortunate it seemed, that the doctor and his man Mayer had overlooked the opera hat. He wondered if they had thought of it since? It was clear that they had not, else he would no longer be kept a prisoner. What was the room beneath the laboratory used for? Its appearance had suggested that it was not used at all—a mere lumber-room, a place for storing boxes and crates. And then there flashed into his mind the thought, where was he now? From the apparent distance of the ceiling, as shown by the beam of light, he concluded that he was lying on the floor, a conclusion which the hardness and coldness of the surface beneath him amply proved. Evidently it was a floor of stone, or cement, not one of wood. A certain sense of familiarity in his surroundings came over him. The faint radiance which was diffused about him by the light cone showed the walls before and on either side of him to be of uniform blackness, unrelieved by any suggestion of windows. He strove with all his power to pierce the shadowy gloom, to come upon some point of recognition, but the darkness baffled him.

In one corner a huge shadow, bulking formless against the wall, suggested the packing case behind which his opera hat had been tossed by Mayer during the search the night before. The thought thrilled him with renewed hope. What more likely place, after all, for Hartmann's deviltries than this silent room beneath the laboratory? If he was lying there now, and chance of escape should come, he might even yet be able to take the missing snuff box with him.

The hours dragged interminably. He was conscious of a keen feeling of pain, a smarting irritation, in his eyes, which caused tiny streams of moisture to trickle beneath their lids and roll unheeded down his cheeks. The muscles of his neck became sore and swollen, from his incessant though useless effort to turn aside his head. A dull pain began to shoot insistently through his temples, and his limbs became numb and cold. The desire to escape from the relentless brilliance of the light cone became unbearable; he felt as though, if relief did not soon come, he would shriek out in a madness of terror. Then the hopelessness of doing so became apparent, and he nerved himself with all the power of his will to endure the ever-increasing torture. Yet this torture was, he knew, largely mental—the actual pain was by no means unbearable; it was only the dull, insistent pounding of the light rays upon his eyes, his brain, from which he longed to escape. With closed eyes and tensely drawn nerves, he waited, watching the endless play of the tracery of light in the dull redness of his eyelids.

The sudden sharp rattle of a key in the door, followed by the turning of the knob, told him that someone was entering the room. He had a momentary vision of a patch of light, yellow against the surrounding blackness, which disappeared almost instantly as the door was closed. Then he was conscious of a shadowy form beside him, and heard the smooth, modulated tones of Dr. Hartmann's voice.

"Well, Mr. Duvall," he said, "how goes the treatment? Memory any better this morning?"

He made no reply. The mockery in the doctor's voice roused him to sudden and bitter anger.

"I'm trying a new modification of the light treatment upon you," Hartmann went on, with a jarring laugh. "Dr. Mentone, of Milan, has great hopes of it. Wonderful thing, these violet rays! Have you read of their use in sterilizing milk? No? The subject would interest you. How is your mind this morning? Somewhat irritated, no doubt. Well, well, that will soon wear off. You've only been under the treatment six hours. Scarcely long enough to produce much effect. We'll make it ten, the next time. It is necessary to increase gradually, in order not to superinduce insanity." He went to a switch on the wall and pressed it, and instantly the cone of light disappeared. Another movement, and the room Was flooded with the yellow glow of an electric lamp, which seemed dingy and wan, compared with the cold brilliance which it displaced.

The dispelling of darkness brought to Duvall's brain a rush of sensations, among which the knowledge that he was once more in the lumber-room beneath the laboratory stood forth with overwhelming prominence. He glanced at Hartmann with reddened eyes. "Let me up, damn you!" he shouted.

The doctor bent over him, his face smiling. "Just a moment, Mr. Duvall. Have a little patience." He began to unbuckle several straps, and presently stood back, with a wave of his hand. "Get up," he said.

The detective's swollen muscles, his stiffened limbs, still retained the sensation of being bound; he scarcely realized that his bonds had been removed. Painfully he crawled to his feet, and stood before the doctor, blinking, trying to collect his faculties. On the floor lay a number of broad leather straps, secured to iron rings which had been let into the cement floor.

His first thought was to make a quick rush at his captor, and after overpowering him, secure the snuff box and dash from the place. His eyes must have shown something of his intention, for Hartmann, stepping back a pace, drew his right hand from his pocket. It contained an ugly-looking magazine pistol. "Don't attempt anything rash, Mr. Duvall. It would be useless. Even should you succeed in disposing of me, which I hardly think possible, you could not get away from my man Mayer, who is waiting in the corridor outside. Enough of this nonsense," he went on, scowling. "I mean to be quite frank with you, my friend. I intend to subject you to this device of mine—" he waved his hand toward the opening in the ceiling—"until you disclose the whereabouts of the snuff box. I know it is somewhere near at hand, either here or in Brussels, for your two assistants, whom I have had released, have been hanging about the place all the morning. If the violet rays have no other effect, they will at least prevent you from sleeping, and my experience shows that loss of sleep, if persisted in, will shatter the best set of nerves on earth. You know what the effect is, for six hours. The next time, as I said some little while ago, we shall try ten—and after that, longer periods, until the process becomes continuous. I am giving you these brief respites, at first, because I have not the least wish to drive you mad—all I ask is the snuff box which you took from my messenger Seltz. Give it up, and you can go at your convenience. But I must have it—even if I am obliged to drive you to the limit. I advise you to save yourself much suffering, and give it to me now."

The detective drew back his arm—his fist clenched. The impulse to drive it into Hartmann's face was overpowering. He turned abruptly on his heel, and made no reply.

Hartmann waited for a moment, then seeing that his prisoner was not disposed to answer, went toward the door. "Max," he called, opening it, "bring in the tray." The attendant at once entered with a waiter containing food, which he placed on a box near the door. "Is that all?" he asked. Hartmann nodded and the man withdrew.

"Think the matter over, Mr. Duvall," the doctor remarked, as he stepped across the threshold of the door. "I shall call upon you again, later in the day."

Duvall waited until the door had been closed and locked, and the doctor's footsteps had died away up the iron staircase. He heard them for a moment, on the floor of the room above, then all was quiet.

In a moment the detective had stepped to the large box in the corner, behind which lay, he believed, the discarded opera hat. At a glance, he saw that it was still there. He was about to stoop and pick it up, when a sudden fear swept over him. Suppose he was being watched. The doctor was in the room above. The presence in the room of the beam of light showed clearly that there must be an opening in the ceiling, into the laboratory. For all he knew, Hartmann might be observing his every movement. He stopped in his attempt to pick up the hat, and pretended to be greatly interested in the box and its contents. After making a careful examination of the labels upon it, he strolled carelessly back to the other side of the room, and ate the breakfast which the attendant had left. He supposed it to be breakfast, although he had no realization of the time. In a moment he felt for his watch, and found that it was still in his pocket. When he consulted it, however, he saw at once that it had run down.

After his meal, he began to feel terribly tired and sleepy. At first he fought off the feeling, realizing that his only hope of freedom lay in keeping awake, with all his senses alert. Then he thought of the nerve-racking hours through which he had just passed; the many more which were likely to follow, and decided that he must have rest at any cost. He threw himself upon the floor, his head pillowed upon his arm, and was soon sleeping the deep sleep which follows utter exhaustion.