this trap to test her. If she was in truth
walking in her sleep, she would, she supposed, walk fearlessly into the
yawning gap before--if her somnambulism was a sham, a trick, she would
hesitate, and her fraud be discovered.

She did not know what to do, as step by step she approached that black
and gaping hole. If she kept up her pretense, if she had sufficient
courage to go ahead, of what would it avail Richard or Monsieur Lefevre,
should she maintain her assumed character at the expense of a broken
leg, or neck? On the other hand, to halt, to hold back, would be to
destroy at once all chance of her being of any further service to her
husband, and that, too, at a time when he most sorely needed her.

These considerations flashed through her brain with the speed of light
itself. She had scarcely taken half a dozen steps before she found
herself upon the brink of the opening, and realized that the next step,
if she took it, might be her last.

Then she suddenly collapsed. The effort was too great--she sank
helplessly upon the floor, her face buried in her arms, her whole body
shaking with the force of her sobbing.

In an instant Hartmann had sprung across the opening and grasped her by
the wrist, while his companion was engaged in rapidly replacing over the
gap the section of flooring which had been removed. Within a few moments
the passageway was as it had been before, and the doctor was dragging
her roughly into the laboratory.

She did not cry out--there was no one from whom she could expect aid.
She drew herself up and faced her captor with dry eyes and a face calm,
though pale. "What do you mean, Dr. Hartmann," she demanded, steadily,
"by treating me in this way?"

He forced her into a chair. "Sit down, young woman," he said, gruffly.
"I have a few questions to ask you."

She did so, without protest, summoning to her aid all her powers of
resistance and will. He should get nothing from her, she determined.

"Why have you come into my house," he presently asked, glaring at her in
anger, "under pretense of desiring medical treatment? What is it you
want here?"

She made no reply, gazing at him steadily--fearlessly.

"What is this man Duvall to you?" he shouted. "Tell me, or it will be
the worse for you both."

Again she faced him, refusing to answer. Her resistance made him
furious. "Your silence will profit you nothing," he went on. "You can do
no further harm here, for I know your purpose. You are wor