e agents who failed in their
duty. If you are interested in learning the method of their execution,
you might take to heart the words of your colleague, Dr. Bird: 'The
clue lies in those windows.'"

Carnes glanced at the windows and gave a cry of surprise. The glass
was opaque, as had been the glass in the doctor's laboratory and the
glass in the infirmary at Atlanta. The fogging however, was much more
pronounced, and the opaque glass gave faintly the same red effulgence
which came from the three bodies.

"What does it mean, Doctor?" he asked.

"I don't know, Carnes," said Dr. Bird slowly. "I foresee that I am
going to have to do a great deal of work on short wave-lengths soon.
It is doubtless the effect of some modification of the black lamp
which has done it. Look out!"

* * * * *

He leaped to one side as he spoke, drawing Bolton and Carnes with him.
A panel in the side of the wall opposite the doorway had slid silently
open and through the opening poured out a beam of fiery red. Full on
the three bodies it fell, and then spread out to fill the room. Dr.
Bird had drawn the two nearest men out of the direct beam, but one of
the secret service men stood full in its path. In the excitement of
entering he had dropped his vitrilene shield and the livid ray fell
full on his defenceless body. As they watched an expression of horror
spread over his face and he strove to move to one side, but he was
held helpless. Slowly he stiffened; and, as the ray bored through him,
his body became semi-transparent and the same dull red glow which
emanated from the three bodies they had found began to shine forth
from him. Bolton strove to break from the doctor's grasp and rush to
the rescue but Dr. Bird held him with a grip of iron.

"Too late," he said grimly. "Chalk up another murder to the arch fiend
who has committed the others. I don't know the nature of that ray and
vitrilene may not be an adequate defence against its full force. We
had better get out of here and attack the place from the rear."

Carefully edging their way around the sides of the room, the five men
made their way out through the door. Dr. Bird slammed the door shut
behind him and led the way out of the building and around to the
rear. A door loomed before them and he cautiously tried it. It gave to
his touch and he entered. As he set his foot on the threshold a
terrific explosion came from the interior of the building.

"Run!