t, and that the shot could
mean but one thing--the nearness of Mortimer FitzHugh and Quade. Why they
should reveal their presence in that way he did not ask himself as he
hurried down into the plain with Joanne. By the time they reached the camp
old Donald had covered two thirds of the distance to the mountain. Aldous
looked at his watch and a curious thrill shot through him. Only a little
more than an hour had passed since they had left the mountain to follow
Joanne, and in that time it would have been impossible for their enemies to
have covered more than a third of the eight-mile stretch of valley which
they had found empty of human life under the searching scrutiny of the
telescope! He was right--and MacDonald was wrong! The sound of the shot, if
there had been a shot, must have come from some other direction!

He wanted to shout his warning to MacDonald, but already too great a
distance separated them. Besides, if he was right, MacDonald would run into
no danger in that direction. Their menace was to the north--beyond the
chasm out of which came the rumble and roar of the stream. When Donald had
disappeared up the slope he looked more closely at the rugged walls of rock
that shut them in on that side. He could see no break in them. His eyes
followed the dark streak in the floor of the plain, which was the chasm. It
was two hundred yards below where they were standing; and a hundred yards
beyond the tepee he saw where it came out of a great rent in the mountain.
He looked at Joanne. She had been watching him, and was breathing quickly.

"While Donald is taking his look from the mountain, I'm going to
investigate the chasm," he said.

She followed him, a few steps behind. The roar grew in their ears as they
advanced. After a little solid rock replaced the earth under their feet,
and twenty paces from the precipice Aldous took Joanne by the hand. They
went to the edge and looked over. Fifty feet below them the stream was
caught in the narrow space between the two chasm walls, and above the rush
and roar of it Aldous heard the startled cry that came from Joanne. She
clutched his hand fiercely. Fascinated she gazed down. The water, speeding
like a millrace, was a lather of foam; and up through this foam there shot
the crests of great rocks, as though huge monsters of some kind were at
play, whipping the torrent into greater fury, and bellowing forth
thunderous voices. Downstream Aldous could see that the tumult grew les