or by twirling the
propeller?

This latter difficulty was quickly solved. Two Mexicans stood at
respectful attention as he approached. Bob was dismayed for a moment,
but then, seeing their awkward salute, he chuckled inwardly. They
mistook him for Von Arnheim and evidently that German officer was a
martinet who exacted a measure of discipline from the slovenly rebel
soldiers.

Cracking an order at them in his best garbled Spanish, Bob clambered
into the pilot's seat. He was understood, and better, was obeyed. One
man gingerly approached the propeller and started twirling it, while
the other went to the side of the plane and helped push it forward.

The propeller began to whirl furiously as Bob worked the starting
mechanism. The Mexicans leaped out of the way. The plane began to bump
ahead.

Shouts of anger burst forth at the same moment, there was the crack of
a rifle, and a bullet sang unpleasantly close to Bob's ears. Out of
the tail of his eye he could see a number of dark figures running
toward him from the grove.

But Bob did not wait to be interviewed. With a swoop, the airplane
left the ground and started upward. His pursuers were so close at hand
they could almost grasp the wheels, as they leaped upward. Yet not
quite. Bullets whistled about him, and several pinged against the
body of the machine with a sharp metallic ring. Bob thanked his stars
that the plane had an all-metal body. Once above pursuit, he was safe
from stray rifle shots.

With a curse the baffled Muller, who had been quick to realize that if
one masquerader was not Morales, then the other was not Von Arnheim,
watched the airplane shoot away at dizzying speed and disappear beyond
the guarding hills to the north.

Then he turned back toward the ranch house, eager to learn how the
pursuit of Jack had ended.

But for young Herr Muller and the Calomares ranch in general the night
alarms were not ended. In fact, they had just begun.

Before Muller on his return trip had reached the belt of trees, while
the search for Jack, who had mysteriously disappeared, went on merrily
within the Calomares palace, and while Bob was yet flying over the
hills to the north, rebel pickets below him were attacked by Mexican
government troops.

It was an attack in force.

"Viva, Obregon," shouted the attackers.

The rebels on the northern rampart of hills defending the natural
amphitheatre where the Calomares ranch was located, fell back
hurriedly. They