Billie wanted to go with them very much; not that he felt any great desire to come into close contact with that grim looking old medicine man; but he disliked being left alone worse still. After his recent experience on the desert he felt like having company, no matter under what conditions.

Of course the others would have much preferred that Billie stay with the animals, but neither of them dared hint as much. He had as much right to go as they did, if he felt so inclined.

So Donald hastily started to fasten the pack mule to a branch. As for Wireless, the broncho had been well trained, as a cow pony always is, and when his reins were dropped over his head he would stand a long time unless something unusual occurred to frighten him.

Adrian was of the same mind, as could be seen from the way he threw his bridle forward, and then landed on his feet.

“Me too,” said Billie, promptly; and with the words he proceeded to fix Jupiter after the same fashion, knowing that the horses would be quite content to stand there in company.

All this had taken place in much less time than it takes to tell it. The Witch Doctor had disappeared from sight, but could not be so far ahead but that they might quickly overtake him, if they were spry.

Donald led off, as it had been his proposition which the others had accepted; and on this account, as well as his familiarity with the customs of these strange cliff dwellers, he might be accorded the position of pilot, during the time they remained in the neighborhood of the Zuni village.

The boy had taken particular note of the place where the strangely attired old medicine man had last been seen; and it took the three chums but a few seconds to arrive there.

Just as the guide anticipated, he found that there was something in the nature of a path worn along the rocks, and among the dead fragments of brushwood. It was as though the Witch Doctor had gone back and forth along this same route many times a week for years and years.

What influenced Donald and Adrian to accept of this sudden opportunity to spy on the Zuni medicine man it would be hard to say. Perhaps Donald, whose father was a mine operator as well as a big rancher, may have had a little notion that he would like to know more about the source of that precious metal which report said the old magician knocked from some wonderfully rich ledge inside the mountain nearby the village. That would not be so very strange after all, though the boy might be taking fearful risks in thus following such a vindictive old fellow as the Witch Doctor was reported to be.

As for Adrian, he did not have the same sort of temptation beckoning him on. In all probability the subject of mines and rich ore deposits would have failed to lure him; whereas the prospect of a pleasant little mystery to be solved would act as a spur.

And somehow, what Donald had told about that mysterious music, the strains of which often floated faintly to the ears of the Zuni people after their medicine man had betaken himself off to one of these famous audiences with Manitou, had taken a firm hold on the mind of Adrian. He hoped that before they quitted the country of the Zunis a chance would arise whereby they could find out if there was really any truth in these stories; and should it prove to be so, learn just what caused the music that the ignorant natives believed supernatural or angel voices.

And as has already been said, Billie went along simply because he was afraid to stay there alone, and not that he felt any particular interest in either gold mines or cherub voices.

Two minutes later, and Donald held up a hand warningly. That was enough to tell the others he had sighted the object of their pursuit. And as they did not wish to let the hideous figure that stalked along ahead know how he was being followed, they hung back until their guide again beckoned them on.

“He’s just gone back of that line of brush yonder,” Donald whispered, as they joined him. “Let’s wait here a minute, to give him a chance to move along. And we can keep an eye on that cliff over yonder; because, unless I’m mistaken, he was heading that way when last I glimpsed him.”

They crouched there and waited, Billie nervously fingering his camera, as if in readiness to use it again should the chance arise.

“There he goes!” ejaculated Adrian, suddenly.

“Oh! where?” asked Billie, giving a start, as if he had at first suspected that the old fellow might have stolen a march upon them; and from the way Billie looked above his head one would think he half expected that that hideous figure would come tumbling down upon them, his arms filled with rattlesnakes, perhaps.

“Over near the cliff, just as I said,” replied Donald, pointing as he spoke.

“I see him, all right,” announced Billie, immediately, as though that were something worth mentioning.

“Looks like he meant to climb up somewhere,” suggested Adrian.

“We’ll watch, and see the circus, then,” added Donald; “but better keep down, so he won’t glimpse us if he happens to look back this way.”

“That’s good advice!” muttered Billie, dropping flat, and then poking his head up as best he knew how, so that he might see without betraying his presence; Billie had not been in the company of these two prairie boys for weeks without picking up at least a smattering of the things they knew.

“Why, he’s gone!” he exclaimed, a second or two later; and commenced to rub his eyes vigorously, as though inclined to suspect that they had played him a trick.

“Did you see that?” remarked Donald, of Adrian; for they had been looking all the time Billie was fussing, and getting himself so nicely fixed that he had temporarily lost track of the medicine man.

“He went behind that twisted cedar, and then seemed to just melt away in thin air,” the other replied, with a vein of wonder in his voice.

“Then he is an old wizard after all, ain’t he?” remarked Billie, hearing this.

“That remains to be seen,” declared Donald. “Shall we go over there, and take a look around, Ad?”

“Sure he ain’t just hidin’ behind some rock?” asked Billie, grown cautious, it appeared, after his recent experiences.

“You can see for yourself that the whole face of the cliff looks open, and there isn’t an outlying stone that would shelter a cat, much less a fellow of his heft,” Donald told him; “how about it, Ad?”

“If you think it’s right, why let’s walk over, and make out to be interested in the formation of the wall of rock,” replied the other. “If he chances to pop out on us, then we can make him believe we’re geologists, and interested in the history of these old-time hills.”

“A good idea, sure it is!” admitted Billie, always wanting to put in his oar, and at the same time willing to give praise where it was due.

Donald no doubt thought the same, even if he only smiled, and nodded his head.

Having thus decided they stepped out from their place of concealment, and in an apparently careless manner walked toward the cliff that reared its head far above, being fully a hundred feet from base to summit.

Billie trailed along in the rear. He did not feel wholly at ease, although in the society of his chums, whom he knew to be capable of holding their own with any ordinary peril. But somehow Billie had an idea that they were taking big chances when they accepted the risk of spying on the Witch Doctor. And he wanted to be in a position to render a good account of himself, in case anything happened.

He had slung his little camera over his shoulder by means of the strap attached for this very purpose; and now held his rifle in both hands, feeling very much of responsibility, somehow or other, because he came in the rear, and let them do all the looking for an explanation of the mysterious disappearance of the old Zuni, while he kept his eyes on the alert for trouble.

Just as Donald had so positively said, there were no outlying stones of any size along the base of this cliff. The two boys had even glanced eagerly upwards more than once, half expecting to discover signs that might tell how the mountain here had once been used by some of the cliff dwellers; but so far as they could see there was not a single hole hewn in that blank wall from top to bottom.

Adrian picked up a piece of stone, as though carrying out the little scheme he had suggested about their pretending to be geologists; and while he and Donald put their heads together, as though they were examining the same, they were exchanging remarks.

“See any sign of the old fraud, Ad?” asked Donald.

“Not around here, that’s flat,” answered the other.

“But we’re directly behind that crooked cedar,” urged the rancher’s son; “and as sure as I’m here, that’s just where I saw him last. And you know as well as I do, Adrian, he couldn’t have slipped away to either side, nor yet climbed the face of this cliff!”

His chum shook his head as he glanced all around; and then stepping closer to the face of the height that arose far above, he scrutinized it carefully.

Then he laughed.

“Tell you what, Donald,” he said, “this makes me think of plays I’ve seen on the stage, where the magician disappears through the face of the rock in a wonderful way; but everybody knows that it’s only canvas, painted to look like the solid wall. Here, though, there’s no such thing; and yet you say he came to this spot and then just went up like a puff of smoke. Take it from me now, that there must be some secret way of getting in back here, if only we had the key to the mystery!”

“Whew! is that what you think too, Donald?” asked Billie, taking time to stare at the wall of rock, which up to now had interested him very little, since it was the Witch Doctor himself for whom he was looking.

“I reckon it must be something like that,” Donald admitted. “We don’t believe in magic, and all that stuff; there must be a real explanation for everything that looks so queer; if, as Adrian says, we only had the clue to the trail. But even the rocks here show no trace of his footsteps, so we can only give a guess how he gets in and out.”

“Huh!” grunted the incredulous Billie; “I reckon, then we’re up against a blank wall right now, in more ways than one; and the old chap’s got us guessing, all right.”