er-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 fee