“Almost forgot this,” he said.  “Your tellin’ me about that there scoundrel of a Greaser put everything else out o’ my mind.  Must be gittin old an’ forgetful.  One o’ these days I’ll forgit my head.”

He would have rambled on garrulously, but Jack interrupted.  He turned the envelope over curiously.  It bore no address or writing of any kind, and was sealed.

“What’s this for, Pete?” Jack inquired.

“Oh, that’s somethin’ Mr. Rollins musta dropped out o’ his pocket at breakfast.  Found it on the floor beside his chair after he was gone.  Will you give it to him?”

“All right.”

Jack returned to join his companions.

“Have we any right to open this?” he said, after explaining how he had obtained the envelope.  “I for one believe that we should.  It may contain valuable information to us.”

“You’re right, Jack,” said Mr. Temple.  “I’m a partner in this oil enterprise, and if one of our trusted employees is a scoundrel we are entitled to know it.  Give me the envelope.  I’ll take the responsibility.”

While the others looked on, Mr. Temple ran a knife along the edge and slit the envelope open.  Inside was a mass of documents and a letter.  Mr. Temple unfolded them, gave one look, then with an exclamation jumped to his feet.

“Great Scott, boys,” he cried.  “This is important.  Luck is certainly with us.”

CHAPTER XIV

THE KEY TO THE MYSTERY

“What is it?” cried Jack, pressing forward.

“Yes, tell us,” demanded Bob and Frank as in one breath.

The three boys crowded around Mr. Temple, who in one hand held the mass of documents and in the other the letter.  He was reading the latter.

“Boys,” said he, “this proves Rollins’s complicity in a plot against us.  But it makes matters more puzzling and complicated, too.”

“How is that, sir?” Jack inquired.

“Well, first of all,” said Mr. Temple, holding up the thick sheaf of papers, “this is Mr. Hampton’s own original list of the leases secured by the group of independent oil operators to which I belong and which he represents here in the field.”

“Is it a copy of the list I recovered from the thief who stole it from Mr. Hampton’s house on Long Island?” asked Bob.

“No,” smiled Mr. Temple.  “It is the original.  That was the copy.  And this letter with it is one written by Rollins to a man in New York City who is one of the minor officials of the Oil Trust.  It is too long to read to you.  But from it I gather that Rollins is a spy in the employ of this official.”

“Say, Dad,” declared Bob, “this is too much for me.  If the Octopus is responsible for our troubles, then where do the Mexicans come in?  And vice versa?”

“That’s what I had in mind, Bob, when I said this discovery complicated matters,” said Mr. Temple.

“Sh,” warned Jack, from the window toward which he was glancing at that moment.  He sprang forward to see better.  “Here comes Mr. Rollins now.  And in a tearing hurry, too.”