the Russian's, "I will remember this. Later, when you
grovel at my feet and beg for mercy, it will be my friend, Operative
Carnes, who will read your doom to you and choose the manner of it. I
can promise you that your death will not be an easy one."

The Russian laughed, albeit the laugh had more of uneasiness than
humor in it.

"When you have me in your power, Doctor, you may do as you like," he
said, "but I do not fear dead men. In another two hours, you will be
among the dead."

He turned to the three Russians who stood behind him.

"Seize him!" he cried.

The Russians leaped forward, but Dr. Bird was not caught napping. The
first one went down like a felled tree before the doctor's fist. The
other two came in cautiously. Dr. Bird sprang forward, feinting. As he
leaped back, his foot struck a rod which Ivan Saranoff had thrust
behind him. He staggered and fell. Before he could recover his
balance, the two burly Russians were on him.

Even then, they had no easy task. Dr. Bird weighed over two hundred
and there was not an ounce of fat or surplus flesh on him. First one,
and then the other, of the Russians was thrown off him, but they
returned to the attack, unsubdued by the crashing blows which the
doctor landed on their faces and heads.

Gradually their ardor began to evaporate. With a sudden effort, Dr.
Bird strove to regain his feet. A crash as of all the thunders of the
universe sounded in his ears, and flashes of vivid light played
before his eyes. He felt himself falling down ... down....

* * * * *

He recovered consciousness to find his feet shackled and fastened to
rings set in the concrete of the cavern wall. His head throbbed
horribly. He raised his hands and found a huge bump on his head, from
which thickened blood trickled sluggishly down his cheek. The cavern
was flooded with light. On the wall before him, a clock told off the
seconds with a metallic tick. He bent down and examined his shackles.

"I'm afraid you can't unfasten them, Doctor," said a sardonic voice.

He looked up to see Saranoff.

"I'm sorry I had to hit you so hard," went on the Russian. "Your half
hour of unconsciousness has lessened by that much the time which is
yours to indulge in an agony of apprehension. Look."

Dr. Bird's gaze followed the Russian's finger. On the floor, twenty
feet from where he was shackled, stood a yellow can with the mark of
the Bureau of Standards on its side. H