mad in a good cause. Inside of ten minutes some German
general will be hearing remarkable news from this station."

"I tell you again you're mad."

"And I tell you again I'm not. I'm a crack wireless operator and this is
my chance to prove it. I'm going up there. All who are afraid can turn
back."

"You know that if you're resolved to go mad we'll go mad with you. What
do you want us to do?"

"John, club your automatic, and hit that officer on the back of the head
with it. Hit hard. Don't kill him, but you must knock him unconscious at
the first blow. Carstairs and I will choke all but a spark of life out
of the operator."

The three emerged from the stairway upon the flat portion of the roof
where the wireless plant had been installed not more than four or five
feet away. They made not the slightest sound as they stole forward, but
even had they made it the two Germans were so deeply absorbed in their
talk through the air that they would not have heard it.

John felt compunctions at striking an unsuspecting enemy from behind,
but their desperate need put strength in his blow. The officer fell
without a cry and lay motionless. At the same instant Wharton and
Carstairs seized the operator by the throat, and dragged him down. He
was a small spectacled man and he was only a child in the hands of two
powerful youths. In a minute or two and almost without noise they bound
him with strips of his own coat, and gagged him with a handkerchief.
Then they stretched him out on the roof and turned to John's victim.

The man lay on his face. His helmet had fallen off and rolled some
distance away, a ray of moonlight tipping the steel spike with silver. A
dark red stain appeared in his hair where the pistol butt had descended.

The figure was that of a powerful man, and the set of the shoulders
seemed familiar to John. He rolled him over, and disclosed the face of
von Boehlen. Again he felt compunction for that blow, not because he
liked the captain, but because he knew him.

"It's von Boehlen," he said, "and I hope I haven't killed him."

Carstairs inserted his hand under his head and felt of the wound.

"You haven't killed him," he said, "but you struck hard enough to make
him a bitter enemy. The skull isn't fractured at all, and he'll be
reviving in a few minutes. He's a powerful fellow, and we'd better truss
him up as we have his friend here."

While Carstairs and Wharton were binding and gagging von Boehlen, John
w