f the apparatus behind
which they stood. Leaned forward eagerly, peering through the glass
screen at the mirror. Manipulated dials and levers.

An inexplicable excitement gripped Mark. He had a sudden, unshakable
conviction that he and the professor were on the verge of incredible
discoveries. Discoveries that would lead him to an explanation of the
strange coma that held Elaine in its grim sway.

His brown eyes fastened on the mirror. The next instant they went wide
with astonishment.

The glass screen behind which he and the professor were standing was
clearly reflected.

But it was merely an opaque surface! Neither he nor the scientist could
be seen behind it!

As if reading his mind, Professor Duchard gave vent to a little laugh.

"'One-way' glass," he explained. "It permits vision in only one
direction." Then the humor went out of his voice. "We may thank God that
science developed it before we are through."

Again he leaned forward, his eyes on the mirror.

An instant later he leveled a quivering forefinger.

"_Look!_"

There, in the semi-darkness where stood the looking-glass, a weird
figure was beginning to glow!

Tension flooded through Mark's veins. His fingers knotted into fists.
His eyes strained to catch the thing which grew upon the mirror's
surface.

Slowly, like some wizard's evil phantasmagoria, the glowing lines came
together. Took form. Painted a figure--

_The figure of the woman in the mirror!_

"That's her!" he cried excitedly. "That's the woman we saw reflected
instead of Elaine!"

Professor Duchard snapped off the machine beside him. He turned on the
lights. Swung around to face his daughter's fiance. His face was grey.
Grim lines of worry etched deep into the flesh.

"So that is it!" he said. "That is what he has done to her!"

There was fear in his voice ... living, breathing fear. That and
despair. The despair of utter hopelessness. His shoulders sagged with
it. The sparkle had gone out of his eyes.

Mark gripped the old man's arm. Blood lust flamed in his own brown orbs.
Every muscle was taut. The cords in his neck stood out like knotted
ropes.

"What is it?" he demanded savagely. "Is it Vance? What has he done to
her?"

Wearily, the scientist pulled his arm away and gestured the other to a
seat.

"I shall tell you," he said. "You will not believe me, but I shall tell
you."

"Yes. Go on. I'll decide for myself whether I'll believe you or not."

The professor s