"I shall
feel assured that you will not go many miles from here."

The remark covered the fact that Montez had all avenues of escape
so well guarded that the young engineers simply could not escape
by flight.

Good nights were exchanged, and the visitors, smiling politely,
departed.

"Now, why on earth did you talk to Don Luis in that fashion?"
Harry demanded, as soon as they were alone. "You know, well
enough, that not even the certainty of immediate death would make
you accede to his rascally wishes."

"I'm afraid I don't know anything of the sort," Tom drawled.
"On the contrary, we may help Montez sell out to the American
visitors."

Harry gasped.

"Tom Reade, are you going crazy?"

"Not that I've noticed."

"Then what are you talking about?"

"Harry, I'm tired, and I think you are."

"I'm sick and tired with disgust that Don Luis should think he
could use us to bait his money-traps with," Hazelton retorted.

"Let's turn in and get a good night's rest."

"Oh, bother!" retorted the junior engineer. "I couldn't sleep.
Tom, I shan't sleep a wink to-night, for dreading that you'll turn
rascal-helper. Tell me that you've been joking with me, Tom!"

"But I can't truthfully tell you that," Reade insisted. "I am
not joking, and haven't been joking to-night."

"Then I wish you'd open up and tell me a few things."

"Wait," begged Tom. "Wait until I'm sure that the few things
will bear telling."

With that much Harry Hazelton found that he would have to be content.
He allowed himself to be persuaded to turn in.

Tom Reade was asleep in a few minutes. It was after two in the
morning ere Harry, after racking his brains in vain, fell asleep.

The next morning it was found that the stranger in the back of the
cook tent had made good his prophecy by vanishing.

CHAPTER XIX

THE HIDALGO PLANS GRATITUDE

Soon after an early breakfast Tom and Harry were afield.

From behind a window in the upper part of his big house, Don Luis,
equipped with a powerful field glass, watched them keenly whenever
they were in sight.

"What on earth are the Gringos doing?" he wondered, repeatedly.
"Are they just walking about, aimlessly? At times it looks like
it. At other times it doesn't."

Then Montez sent for Tisco and discussed with him the seeming
mystery of the actions of the young engineers.

"Don't ask me, Don Luis," begged the secretary. "I am not clever
at guessing riddles. More, I have not