een. 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