"Don't look just now," said Frank, as they sat at a table; "but Abajo has taken his seat right back of you. And it wasn't accident, either, that made him do it; I believe he has been set to watch us!"
From time to time, as they ate, Frank would report as to what the half-breed was doing; and while nothing occurred to actually prove the fact, still he saw no reason to change his mind.
"And I'm going to find out if he's keeping an eye on us, so as to report to his employer, Eugene Warringford," Frank announced, as they were drawing near the end of the meal.
"That sounds good to me," Bob remarked; "but how will you do it?"
For answer Frank drew out a paper from an inner pocket.
"You see this document," he observed, with a solemn look. "Well, it's only what you might call a dummy, being just an invitation I received a little while back to invest in some worthless mines over in the Hualpai Mountains of Mohave County. I kept it, meaning to figure out how these sharpers work their game. Now, when I hand you this, look deeply interested, as though it might be connected with the finding of Uncle Felix."
"Oh! I see your move, and go you one better, Frank."
For some little time they seemed to be conversing intently. Frank would occasionally tap the document, which he had sealed up in its envelope, as though he laid great stress on it. Finally he placed it on the table alongside his plate, and kept on talking.
Shortly afterward the boys left the table in apparently such a hurry that they both forgot the envelope that lay there, half hidden by a napkin.
Passing out of the room, they dodged back, and peered around the corner of the doorway.