The hours of the night dragged along on leaden feet. Once she heard the closing of a door, and the sound of footsteps echoing faintly upon the cement floor of the lower corridor. Within the laboratory all seemed dark. Evidently the doctor was not there. Then she heard, through her half-opened door, noises of persons walking in the lower hallway of the main building and after that the sharp closing of a door. She concluded that Hartmann had gone into his office.

The woman on duty in the hall sat in her chair, reading and yawning. After a time, Grace heard the faint ringing of her bell, and the woman, after consulting the indicator, began to descend the stairs with a surprised look upon her face. It seemed like a providential opportunity. She slipped quietly through the doorway and sped as swiftly as she could down the hall.

She reached the door opening into the corridor, without hearing or seeing anything to cause her alarm, and passed through it unseen. As she closed it behind her, she fancied she heard someone walking quickly along the corridor beneath. The passageway in which she stood was in reality nothing but a covered bridge, a few feet wide, built for the sole purpose of providing a means of passing to the laboratory from the second floor of the main building. Beneath it, a similar passageway connected the ground floors of the two buildings.

She realized that anyone in the corridor beneath her could readily hear her footsteps on the wooden floor above, and stood, hesitating, just inside the door, waiting until they should have passed. In a few moments, the sounds below ceased, and silence again reigned.

With great timidity and caution, she began to walk toward the laboratory door. In the center of the corridor, and half way down its length, a single electric lamp shed a dim light on her path. She realized that if, by chance, anyone should be within the darkened laboratory, they could readily see her approaching, and therefore assumed once more the manner and bearing of a person walking in their sleep. She had passed the light in the middle of the corridor, and was nearing the darkened laboratory door, when suddenly she heard a faint click, and almost at once the laboratory was brilliantly illuminated.

By the light which suddenly flashed upon her, she saw two figures standing in the open door of the laboratory, watching her intently. One of these figures was Dr. Hartmann, the other the tall blond man she had seen with him in the laboratory several nights before. But it was not the sudden appearance of the two watching figures which caused her heart to sink, and a cold perspiration to break out upon her forehead. The sudden rush of light upon the floor of the passageway had shown her something else—something far more strange and terrifying. As her gaze swept ahead, she saw that, for a space of some four or five feet, in front of the laboratory door, the wooden planking which constituted the floor of the passageway had been removed, and instead of the solid foot-way there yawned blackly an impassable opening, through which, in another moment, she would plunge headlong to the concrete floor of the corridor beneath.

The sight filled her with dismay. She realized at once why Hartmann and his companion stood there watching her—why the section of flooring had been removed. He had evidently become suspicious of her movements, the night before, and had laid 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.