"Whew!" exclaimed Bob, presently, as the sound of retreating hoofs began to die away; "what d'ye think of that, eh, Frank?"
"Indians?" queried the Kentucky boy, eagerly.
"Well," replied his chum, "not so's you could notice. Say, now, you didn't see any feathers on their heads, did you? And I sure heard the fellow nearest us say something that only a white man would remark, when his horse stepped into a hole, and almost threw him over its head."
"Cow punchers; or perhaps rustlers?" continued Bob, anxious to know.
"What would cowmen be doing away off here, tell me that, Bob? And lugging along a bunch of extra mounts, too, in the bargain? No, I rather think, Bob, that those fellows must have some of Mendoza's cattle rustlers. And they've been making a dandy raid on some ranch's saddle herd; or I miss my guess."
"Perhaps the Circle outfit had gotten careless," suggested Bob.
"I sure hope not, for the boys have had plenty of warning; and I reckon Bart Heminway is some too good an overseer to permit such a raid. I'd rather believe it was the X-bar-X outfit that has gone and got nipped this time. But stop and think Bob; what d'ye expect takes these cattle-rustlers over this way right now, headed straight for the canyons of Thunder Mountain?"
"Oh, I see what you mean!" exclaimed the taller lad, immediately. "Perhaps the secret hiding place of Mendoza and his crowd of cattle thieves may be somewhere around this same old rock pile. It'd be just like the tricky rustler to have a hide-out where nobody else ever came!"
"Now, why didn't somebody ever think of that before?" ejaculated Frank, in a tone of mingled surprise and disgust.
"Looks easy, doesn't it, after we've run across a clue?" admitted Bob, laughing softly. "You remember what they said about discovering America, after Columbus did it. But supposing this thing does turn out to be true; how's it going to affect our little business, Frank? Oh! say, I wonder if that crowd can have anything to do with the rumbling of the mountain?"