The others agreed eagerly.  They were in the act of leaving the table when Mr. Temple appeared.  They crowded about him with questions.

“Easy, easy there,” he protested.  “I’m hungry as a hunter.  Suppose you boys wait outside for me while I get a bite, and then I’ll join you.”

When Mr. Temple emerged, he lighted a cigar and leaned against a pillar.  The boys stood about him.  For several moments he was silent, staring out over the expanse of desert to the hills beyond, all shimmering beneath the heat of the summer sun.

“It’s a long story,” he began, “but I’ll simplify it for you.  Rollins held the key to the mystery.  He has a family back East, an invalid wife, a son in college, a daughter just preparing to enter college.  All that takes money, for doctor bills and school bills and clothes for the girl.  Rollins was a poor man on a salary.

“He needed money and couldn’t see his way to getting it.  Then a minor official of the Octopus put temptation in his way by making him a proposition.  Mind you, he wasn’t one of the big men of the Oil Trust.  I feel certain they know nothing about all this.

“This man proposed that Rollins obtain certain inside information about the independent oil operators and sell it to him.  Rollins wanted to, but couldn’t get the information.  It was too closely guarded by Mr. Hampton.

“It was then that another temptation came Rollins’s way.”  Mr. Temple paused.  “A weak man seems to carry certain earmarks that draw scoundrels to him, boys,” he said.  “It was so with Rollins.  At this moment a representative of Calomares, the Mexican landowner who is backing the northern rebels, sought him out with a proposition that he betray his employers.  The rebels, as I suspected, wanted to make trouble for President Obregon, of Mexico, by embroiling him with the United States.  And the way they wanted to set about it was by raiding the independent oil operators.  They needed a spy at our headquarters, and they proposed that Rollins should become their man.

“Then Rollins had an inspiration.  He told the Mexicans that if they would help him, he would aid them.  It was agreed.  The agent who had acted for Calomares in the negotiations was this German, Von Arnheim, an aviator and a German secret agent in Mexico during the war.  He took the man Morales with him to Mr. Hampton’s Long Island home to steal the duplicate list of independent leases and other data which Rollins had learned was kept there.”

“That’s where I came in,” grinned Bob.

“Yes,” said his father, “and it was because you foiled them that Rollins came into possession of Mr. Hampton’s own original copy of the list and other data.  For he stole it from Mr. Hampton’s effects after Von Arnheim and Morales had carried him away captive in our airplane.”

“How about this attack on us yesterday?” asked Jack.

“As you suspected, it was for the purpose of capturing me, too,” said Mr. Temple.  “And Rollins had let the bandits know when I would arrive.  Remedios was his go-between.”