"'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.