d was hardly strong enough to
make this sound. For a full five minutes he listened without moving
his horse. Then came the thing for which he waited, a phrase of melody
undoubtedly from human lips.

What puzzled him most was the nature of the music. As he rode closer
to the trees it grew clearer. It was unlike any song he had ever
heard. It was a strange improvisation with a touch of both melancholy
and savage exultation running through it. Calder found himself nodding
in sympathy with the irregular rhythm.

It grew so clear at last that he marked with some accuracy the
direction from which it came. If this was Silent's camp, it must be
strongly guarded, and he should approach the place more cautiously
than he could possibly do on a horse. Accordingly he dismounted, threw
the reins over the pony's head, and started on through the willows.
The whistling became louder and louder. He moved stealthily from tree
to tree, for he had not the least idea when he would run across a
guard. The whistling ceased, but the marshal was now so near that he
could follow the original direction without much trouble. In a few
moments he might distinguish the sound of voices. If there were two or
three men in the camp he might be able to surprise them and make his
arrest. If the outlaws were many, at least he could lie low near
the camp and perhaps learn the plans of the gang. He worked his way
forward more and more carefully. At one place he thought a shadowy
figure slipped through the brush a short distance away. He poised his
gun, but lowered it again after a moment's thought. It must have
been a stir of shadows. No human being could move so swiftly or so
noiselessly.

Nevertheless the sight gave him such a start that he proceeded with
even greater caution. He was crouched close to the ground. Every inch
of it he scanned carefully before he set down a foot, fearful of the
cracking of a fallen twig. Like most men when they hunt, he began to
feel that something followed him. He tried to argue the thought out of
his brain, but it persisted, and grew stronger. Half a dozen times he
whirled suddenly with his revolver poised. At last he heard a stamp
which could come from nothing but the hoof of a horse. The sound
dispelled his fears. In another moment he would be in sight of the
camp.

"Do you figger you'll find it?" asked a quiet voice behind him.

He turned and looked into the steady muzzle of a Colt. Behind that
revolver was a thin,