have rigidity
enough to pull the key over the little bump which held it. A glance at
the clock threw him into an agony of despair. A full hour had passed
since Saranoff had left him. Carnes might even now be walking into the
trap which had been laid for him.

He rose to his feet and thought rapidly, twisting the wire idly around
the knife as he did so. He glanced at the work of his hands, and an
oath broke from his lip.

"Fool!" he exclaimed. "I deserve to die! The means for liberation were
in my hands all the time."

* * * * *

With feverish activity, he ripped open the flashlight. He held the two
ends of the wire against the terminals of the light battery and
touched the knife to his steel key ring. To his joy, the ring adhered
to the knife. Under the influence of the battery, the wire-wrapped
knife had become a small electromagnet.

In a moment the doctor was prone on the floor. He tossed the knife
out to the key. His aim was good and it fell directly beyond. With
trembling hands he drew the knife toward him. It reached the key.
Scarcely daring to breathe, he pulled it closer. The key had risen
over the ridge which had held it, and was adhering to the knife. In
another moment, he stood erect, freed from the shackles which had
bound him.

He made for the door at a run, but a sudden thought stopped him. The
clock showed him that an hour and twenty minutes had passed.

"Carnes must be nearly here!" he cried. "If I go blundering out, I'm
liable to run right into the trap they have laid for him, and then
we're both gone. If I yell to warn him, the fool will come ahead at
full tilt. What the dickens can I do?"

His gaze fell on the can of radite. The wires leading to the
interrupter fuse gleamed a dull gold with a malign significance.

"If Carnes and I are both washed out, there will be only Thelma left.
She can't fight Saranoff alone. Carnes knows the man and his methods.
There is only one way that I can see to warn him out of the trap."

He shuddered a moment. With a steady step he walked across the cave to
the can of deadly explosive. A pair of pliers lay on a nearby bench.
He picked them up. He dashed his hand across his face for a moment,
but looked up with steady eyes. With hands that did not tremble, he
bent down over the can. With a quick snip, he severed the wires
leading to the can of radite.

* * * * *

Operative Carnes jumped ashore a