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.