endid structure.

He gazed around him. Nobody in sight. Shrubbery intervening prevented
him from gaining a clear view of the house. He started to skirt the
bushes.

Meantime, not far away, the conversation between Jack and Muller was
nearing a climax. Approaching the pretended Morales, Muller asked what
he had tried to convey in his radio call, explaining it had been so
interfered with by another mysterious call as to be non-understandable.
Not knowing Muller was the radio man at the ranch, Jack was nonplussed.
Again he answered that he could not be delayed, and started to withdraw.
Then Muller laid a detaining hand on his arm.

"Keep it to yourself, if you want to," Muller said. "But I know
something happened at the cave and I have already reported so to the
Don. First I thought you were trying to radio from the cave. Now here
you come by airplane. There's--"

"What do you mean?" growled Jack gruffly, although secretly alarmed.

"I mean there's something wrong," Muller said.

Muller still had no suspicion that the man before him was other than
he pretended to be. Merely he was trying to pry into a matter that had
aroused his curiosity. Jack, however, thought he was on the eve of
being discovered, and was alarmed.

At this moment Bob, skirting a clump of bushes on the lawn below, came
in sight of the two figures and halted.

He saw Jack wrench his arm from the other's grasp and turn to stride
away. He saw the other raise an arm as if to stay Jack. And he saw the
movement flip Jack's low-pulled hat from his head. It was accidental,
but to Jack and Bob--the actor and the observer in this little
drama--it seemed to be by intent. It is possible Jack still might have
saved the day, had he stooped quickly, recovered his hat and clapped
it on again before Muller could have seen his features.

As it was, however, Jack thought he was discovered. And he turned to
deal with Muller. Then, in truth, he _was_ discovered. Muller cried
out in amazement. Then Jack landed a stinging blow on the mouth which
sent the young German toppling to the marble pave.

At Muller's shout, several rebel sentries, who had been snoozing in
the shadows beside the palace, instead of mounting guard, were
startled into instant wakefulness. They came trotting in bare feet,
long rifles in hand, and ran up the wide flight of steps.

Bob started forward to help Jack. The latter, however, took one look
at the sentries and then dashed into the left w