ll you mind letting me lead the way for a little while,
sir?"

"Go ahead, of course," said Dick. "In such work as this we rely upon the
sergeant and you."

"Then I'd like to take a look at those heel prints also."

Dick thought he detected a quiver of excitement or emotion in the
voice of Shepard, always so calm and steady hitherto, and he wondered.
Nevertheless he asked no questions as he led the way out of the ravine.

The sergeant showed the heel prints to Shepard, and beyond question they
had been made by a woman. By careful scrutiny they found a half dozen
more leading in a diagonal direction up the side of the mountain, but
beyond that the ground was so hard and rocky that they could discover no
further traces.

"You agree with me that the tracks have just been made?" said the
sergeant to Shepard.

"I do," replied the spy, his voice showing growing excitement, "and I
think I know who made them. I didn't believe it at first. It seemed
incredible. I want to try a little experiment. Will all of you remain
perfectly still?"

"Of course," said Dick.

He took a small whistle from his pocket and blew upon it. The sound
was not shrill like that of Slade's whistle, but was very low, soft and
musical. He blew only a few notes. Then he took the whistle from his
lips and waited. Dick saw that his excitement was growing. It showed
clearly in the spy's eyes, and he felt his own excitement increasing,
too. He divined that something extraordinary was going to happen.

Out of the cedars to their right and a little higher up the slope came
the notes of a whistle, exactly similar, low, soft and musical.

"Ah, I knew it!" breathed Shepard. He waited perhaps half a minute and
then blew again, notes similar and just the same in number. In a few
moments came the reply, a precise duplicate.

"We'll wait," said Shepard. "She'll be here in a minute or two."

Dick and his comrades looked eagerly toward the point from which the
sound of the second whistle had come. This was something amazing,
something beyond their experience, but the excitement of Shepard seemed
to have passed. His face had become a mask once more, and he was waiting
with certainty.

Dick's sharp ear caught the sound of a light footstep approaching them,
evidently coming straight and with confidence. He realized that
until now he had not really believed, despite the footprints, despite
everything, that a woman was on the mountain. But he k